Stern Tech School: Flipper Maintenance

Stern Pinball·video·17m 47s·analyzed·Mar 26, 2025

Analysis

claude-haiku-4-5-20251001 · $0.016

TL;DR

Stern Tech School: Complete flipper maintenance guide covering diagnosis, part replacement, and reassembly.

Summary

Stern Pinball's Kyle provides a comprehensive technical guide on flipper maintenance and rebuilding, covering wear diagnosis, component replacement, assembly procedures, and critical adjustments like end play and alignment. The video emphasizes that flippers are wear items requiring periodic maintenance, with the crank and link being the primary components that deteriorate and affect gameplay performance.

Key Claims

During a standard 3-minute 3-ball game, players actuate each flipper hundreds of times, making them wear items that affect gameplay
high confidence · Kyle (Stern Pinball), opening statement on flipper wear
The crank and link is the primary component that wears out on a flipper assembly, causing loss of strength and crispness
high confidence · Kyle identifies this as the main wear component during technical explanation
When replacing crank and link, the coil stop must also be replaced because these parts mate together and wear as a pair
high confidence · Kyle emphasizes this replacement requirement and demonstrates wear patterns
Proper flipper end play should be approximately 1/16th inch or about one millimeter (roughly two credit card widths)
high confidence · Kyle specifies measurement during assembly and testing phase
Newer Stern games use Allen head cap screws (5/32 inch) for coil stop attachment, while older games used 5/16 head screws requiring a different tool
high confidence · Kyle distinguishes between coil stop screw types and required tools
The coil sleeve should be replaced during flipper rebuild because a worn plunger can mushroom and create friction inside the sleeve
high confidence · Kyle demonstrates wear deformation and explains friction problems
Stern Pinball is producing educational tech school content demonstrating ongoing commitment to operator and owner education
high confidence · This video is part of an established educational series (referenced as 'another Stern Tech School video')

Notable Quotes

“With the flippers being the primary way you interact with a pinball game, a like standard 3 minute three ball game of pinball you could actuate each flipper you know hundreds of times and they are wear items.”
Kyle (Stern Pinball) @ Opening — Establishes the fundamental concept that flippers are consumable components requiring maintenance
“The primary way most people will notice a flipper is starting to wear is it will not feel nearly as strong or crisp as a new game when you first purchase the game.”
Kyle @ Wear diagnosis section — Provides practical guidance for players to identify flipper degradation
“When this plunger starts moving into the solenoid, it having to take up that slack, that slop there, that directly relates to a lot less force imparted on the ball.”
Kyle @ Mechanical explanation — Explains the mechanical relationship between wear and gameplay impact
“To rebuild your flippers you really only need one tool: a 5/32 inch Allen wrench.”
Kyle @ Tools section — Emphasizes accessibility of flipper maintenance for home owners and operators
“We need to have about a 1/16th of an inch, maybe you know, a millimeter or so—a teeny amount of up and down play—so the flipper pawl, the square section here, the crank, does not bind up against the flipper bushing.”
Kyle @ Critical adjustment section — Specifies the precise end play measurement critical for proper flipper function
“I can see this is moving a bit. I can also hear a slight clunking, just a little bit when I move it up and down. That's how I know that I have just enough end play in this flipper.”
Kyle @ Testing phase — Provides tactile/auditory feedback for verifying correct end play adjustment

Entities

KylepersonStern PinballcompanyStern Tech Schoolevent

Signals

?
community_signal: Stern Pinball producing educational tech school content demonstrates ongoing commitment to operator and owner education/support
high · Entire 'Stern Tech School: Flipper Maintenance' video is part of an established educational series (referenced as 'another Stern Tech School video' at conclusion)

Transcript

youtube_auto_sub · $0.000

0:05

hello I am Kyle with Stern Pinball and in this video we are going to go over flipper maintenance with the flippers being the primary way you interact with a pinball game a like standard 3 minute three ball game of pinball you could actuate each flipper you know hundreds of times and they are wear items they do wear out and when they wear out it can and will affect gameplay right so the primary way most people will notice a flipper is starting to wear is it will not feel nearly as strong or crisp as a new game when you first purchase the game might be harder to make it up ramps you might notice that it drags a little bit maybe it doesn't reset as smooth as it did when it was new the primary component that wears out on a flipper assembly is what we would call the crank and Link here is a uh well used uh crank and Link keep your eye here on the link and watch how much Movement we get when I try to compress it and then pull it apart there's a lot of slop there why does this cause problems so the way that the flipper Works which we will see here in just a moment the solenoid will energize and attract this plunger which then starts a chain of movement when this plunger starts moving into the solenoid it having to take up that slack that slop there that directly relat to a lot less force imparted on the ball when you start to go you know try to make a ramp or something like that how do we fix this we replace this unit we can replace the entire crank and Link when you replace the crank and Link we also want to make sure we replace the coil stop the reason why this also needs to be replaced is because they mate together when these things slam into each other let's take a look at the assembly and how they kind of all interact with each other so the entire flipper assembly is comprised of the base the coil stop the solenoid the uh there's a stopping bracket here that holds the coil in place you've got your crank and Link and plunger assembly here uh you've got an end of stroke switch here you have a flipper bushing which is underneath the crank uh The Flipper P here uh which is kind of hidden um but the flipper bushing is what allows the actual flipper bat above the play field to pass through and then attach to the uh crank and Link here how this works simply the solenoid here energizes creates a magnetic field it pulls the flipper plunger here in which then rotates The Flipper bat which is this uh circular bit here in The Flipper crank or the p and that rotates The Flipper

3:04

I'm going to hold the top end and I'm going to wiggle the plunger a little bit if you keep your eyes here on the link I'm on the top side rotating The Flipper bat I'm holding the plunger in place and we've got that bit of free play right there it's a little worn but it's not too bad to rebuild your flippers you really only need one tool a 53 seconds inch allen wrench um here are some examples a 53 seconds in Allen driver a 53 seconds in T handle Allen driver this is really useful because these are torqued rather strong um so you might not be able to loosen them by just using a driver or what most people will have at home is a Allen key set and having a 53 seconds inch Allen key like this uh will also do the only caveat to the tools you'll need to rebuild a flipper is in the last few years we did switch to using the Allen head cap screw is shown here that uses the 530 seconds to remove on older production games the coil stops were held in with a 5/16 head screw here it's a 5/16 head with a 1032 thread pitch so if yours does have these silver screws that hold the coil stop in place you will need a 5/16 in nut driver to remove those from The Flipper base plate all right so to disassemble your flipper we need to remove the two screws that hold the coil stop to the assembly if you don't have a driver or a t- handle which makes things very easy to get in from the top and to loosen that screw and drive it out um I can show how we can use a standard Allen key and some tight spaces we're going to want to use the shorter side to drive the screw uh because doing that allows us to use the torque of the longer side of the key use leverage to loosen the uh screw here we're going to want to remember left we're going to turn this thing down and towards me at this point it might be loose enough to use the long side of the Allen key to be able to spin this off quicker like that so now we'll use our Allen key to remove the other screw once this screw comes off the coil and coil stop will be loose and they're going to want to move down we'll be able to move the coil upwards and we can pull our coil stop out of the way this wave washer is able to kind of tension the free space that exists between the coil stay and the coil stop to keep the flipper coil the solenoid itself from moving or vibrating so make sure to keep that and uh don't lose it now with the old coil stop removed and set aside we can snake The Flipper solenoid out of place place here almost every coil on a pinball game has a sleeve um this sleeve lines the inside of the bobbin a coil is a wire that is wrapped around a bobin which is this Frame uh this nylon frame and the sleeve takes up the slack on the inside let's examine some things that happen as the coil actuates the stop stops the plunger that's what keeps the flipper movement arrested right and like I mentioned earlier these wear together so you want to make sure you replace these as a pair what happens when you have metal slamming against metal the tip of the plunger starts to deform it flattens and uh starts to wear down the flipper plunger what happens then is it starts to get a bit of an edge to it this is another part of where we were going to start losing power in our flippers when you get a mushroomed over top the end of this can become wider than its prescribed diameter and when it moves inside of the sleeve it can create a lot of friction so not only do we want to make sure we replace the plunger in the stop as a pair when we rebuild our flippers it is a good idea to replace the coil sleeve now with those parts removed we can take our Allen key again and we are going to loosen the flipper PW or The Flipper crank off of The Flipper bat's shaft but here uh what I'm going to do is I'm going to hold the flipper in place and I am going to loosen like so with it Loose we can start to twist and pull the flipper out through the top of the Playfield and now our p is loose with the flipper bat removed we can now remove the crank and Link the last step we have is to remove the flipper return spring from its uh stay which is screwed onto the crank or P here this process can be a little tricky but what we need to do is get the uh small opening on the spring off of the stay bracket I'm going to try to push it up and bring it around just like that and now with the spring removed we can remove the plunger and Link from our flipper plate now that we have all of the old flipper Parts off of The Flipper base uh one thing I do like to check is the flipper bushing itself the way I like to do that is I'll grab a screwdriver or you can use the flipper bat and what I'll do is put the screwdriver inside the flipper bushing and start to apply a bit of pressure in a circle and take a look to see if you can see the flipper bushing cracked around its uh between its flat portion and the portion that sticks out towards you if the flipper bushing is cracked that will also cause a lot of um undesired play in The Flipper um and can also translate to weak or bad performance since this game is uh not heavily used The Flipper bushing is fine the first thing we're going to want to do is grab our a flipper crank and Link you will purchase them and they will be assembled with their switch actuators on on them uh the switch actuator is in place with the spring plate there is a left and a right if both of these are not marked there's one trick that I've learned to be able to tell them apart if you notice on the switch actuator there is a rivet and kind of a hollow section um it kind of turns into a cup if you face this round rivet and the cup away from you on both of these when the switch actuator is facing the right it is the right side uh crank link if it's on the left it's the left side uh we're doing the right flipper so I'm going to use the correct side what we'll do is take the uh crank and we'll kind of fold it into the position that it naturally sits in and we'll lay The Flipper plunger through the coils stay here and I will stick the uh shaft of The Flipper through the flipper bushing on the uh top side of the Playfield and we will slide it into the hole in The Flipper PW here and this this will help just give us a place to kind of hang the flipper pow and keep it from moving around too much um while I'm here I'm also going to hand tighten this screw as much as I can our next step is to reattach the flipper return spring want to catch the side of the spring that has the opening into this small hole right here now with the spring reattached we're going to insert our new coil sleeve into the coil the side of the coil with the solder lugs goes away from the coil stop the flanged end of the coil sleeve goes at the coil stop so we are going to insert it like so kind of in one Fell Swoop we're going to take the coil slide it up over the plunger on the plunger and Link put the wave washer on to the coil stop and press it in place so the core of the coil stop is in the center of the coil and we can kind of pinch it in place here while we go for our Hardware we'll get our cap screws now that we've started the screw we can drive it in with our Allen key uh we're not going to tighten it down all the way we're going to want to start the other screw first before we torque it in place now with both of the coil stop screws snug we're going to torque them in place so we will position our allen wrench in a way that allows us to tighten it a good swing of the wrench here so now we have everything pinned in place uh we are going to need to tighten the crank and Link down around the shaft of The Flipper bat there's an amount of free play or end play that we need between the flipper bushing and the bottom of the flipper PW we need to have about a 116th of an inch maybe you know a millimeter or so a teeny amount of up and down play so the flipper P the square section here the crank does not bind up against The Flipper bushing so what I'm going to do is we're going to roughly set the flipper right now and I'm going to use my Allen key to kind of just take up some of this slack in the screw we're going to get it snug but not tight but once we get to a point of resistance The Flipper will move the reason this is important is because this is where we are going to need to set the level of The Flipper the angle of The Flipper on the Playfield and also adjust in the end play for the purpose of showing this to the camera I have put the play field down into the forward service position but what we need to do now is to align the flipper with its indentation on the Playfield these are used uh for you and for the factory to line up the flippers to get them hopefully set up right the first go so with the flipper again it's rotating the crank and Link underneath the play field but it's still loose enough for me to be able to slide it so our goal is to try and align the tip of the flipper with this small indentation on the Playfield the next step is a critical step and that is getting the end Play Between The Flipper crank and Link and The Flipper bat Set uh so it isn't binding up against the bushing I'm going going to use um two uh credit cards take these and slide them underneath the flipper and what that will help with is keeping that spacing close again trial and error might be the best way to get this right so now that we have the credit cards in place to kind of set that uh depth the the play I'm going to raise the play field back up that point it's a little bit easier to tighten up the hardware with the crank being tightened Down The Flipper shouldn't move but again trial and error we're going to need to kind of be on both sides while we're working on tightening this down I'm going to rotate the flipper ever so slightly so the crank is not resting against this rubber stop and I'm going to feel for the end play and I can feel just a slight amount of up and down play that's what we're looking for um Ser about two credit cards widths a very small amount I feel like I've got good end play before I tighten it down and drive it home going to double check that the flipper hasn't drifted off of the Mark if it has give it a teeny adjustment we're going to try and get our tool here on the screw and we are going to tighten once we give it a few tight uh turns again we're going to go back on the other side of the Playfield and double check to make sure that the flipper is still on its mark it is still on its Mark so we're good at this point we are going to just kind of drive it all the way home as I tighten this screw I am holding the crank and Link uh pushing it up against the rubber stop here to keep it in place so it doesn't want to rotate or shift when I am trying to tighten the screw down once we have it tightened down we want to double check our flipper end play we want to make sure that this adjustment is still good again trial and error and feel I can see this is moving a bit I can also hear a slight clunking just a little bit when I move it up and down that's how I know that I have just enough end play in this flipper if I can see this thing moving a lot too much you need to go back in there and you need to set that end play right if you don't see it moving move it all or hear it move it is too tight and it's going to bind you'll need to redo it and get that proper amount of endplay once the flipper crank is tight once we've confirmed we have uh enough uh free play the last thing we want to do is make sure that the end of stroke switch is not interfering with the flipper crank at all and that when The Flipper reaches its end of stroke this switch actuates just a little bit here we're looking for the switch to be open maybe an eighth of an inch uh once the flipper is at its full stroke with everything back together the next step is to put the play field down and play a couple Test games remember the things we're looking for is if the flipper starts to drift upwards we need to get back in and retighten The Flipper bat shaft in the crank if it is starting to bind or it feels like it's getting stuck or not returning back to its rest position that might mean we do not have the free play set correctly so you'll have to readjust that thanks for watching another Stern tech school video