EM Gottleib Jumping Jacks stepper unit

(Topic ID: 219061)

EM Gottleib Jumping Jacks stepper unit

By swtrains

5 months ago

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  • 9 posts
  • 5 Pinsiders participating
  • Latest reply 5 months ago by CactusJack
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#1 5 months ago

The stepper unit under the playfield (labelled as a bonus stepper) seems to have seen better days. I have eased of the linkages so it has a smoother action and cleaned the brass contacts. But what really concerns me is play in the centre bush.

You can wiggle the contact plate and the stepping cog about a mm. What I don't want to do is try and dismantle anything without seeking expert advice on here!

Can the central bush be easily accessed? How can I dismantle the unit to get to it? Are such things as replacement bushes available? In one of the photos, a central plastic part can be seen, which houses the central bush - are these available?

I'll try calling PBR, but describing stuff over the phone is never easy, and perhaps you guys can guide me a little before I make that call.

Strangely, I can find no record of anyone else experiencing bush wear at this point.

Many thanks! Rick

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#2 5 months ago

Seems like I had this issue a few years back with another Gottlieb EM. Is there a set-screw that tightens to make that center piece not wiggle? Seems like there is.

#3 5 months ago

There seems to be a hex bolt behind the bakelite disc, but I presume that is just to secure the assembly to the central shaft. Love to be proved wrong, but I don't think the slop in the shaft could be eliminated by adjusting a set screw. Get right back to me if I'm wrong!

In the meantime (and as an insurance ) have ordered the relevant part from pbr - D16274 Nylon shaft bushing @ 2.20ea - if any one can suggest a tear down sequence for the stepper, this noob would be most grateful!

Again, thanks to all - Rick

#4 5 months ago

I've never seen that bushing wear out. It makes zero sense that a low speed, low load, self lubricating (no lube required) bushing with no radial force to speak of would wear out.

I believe that when you pulled out the works on the gear side, you upset the axial position of the arms that engage the gear. Indeed, when I look at your second picture, the shaft seems to be about 1/16" low in the hole..

The arm needs to engage the gear as shown by the yellow arrow. If the step is under the gear, then this is the likely cause of your problems.

Teardown sequence

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#5 5 months ago

Thanks for getting back to me, and also for the link!

I agree with your observations re wear - does seem unlikely.

I'm going to explore what you have said over the next few days (I'll wait for my bits to arrive, just in case) - but please note I haven't dismantled the stepper yet, so your comments indicate that a previous owner has been fiddling. I'll see if I can make good!

#6 5 months ago

In my opinion, 1mm of wear wouldn't be too much an issue. The crucial thing is that the unit itself steps up and down smoothly without any binding and that the contacts on the disk make a nice central connection on the brass contacts.
I'd check those springs for decent tension too. If these are tired then the unit will be erratic; I'd always fit new ones as a matter of course. PBR sell kits for these and they are well worth the money.

#7 5 months ago

Good to hear from you again, Classicpinballs! I deliberated about including the spring pack in my pbr order, but felt the existing springs were still good, so held back. That decision may yet come back to bite me.

I've yet to dismantle and clean the unit fully, but a superficial clean and gentle lubing (I know its not allowed) of the pivot points has improved the unit quite a bit. The main sticking point was when the switch follower fell into the bakelite notch, and struggled to get out - and I think that is where the slop in the central bush is not allowing it an even surface to follow.

I agree totally with Newmantjn that there should be no wear here - but there is. It must have led a tough previous life.

I'll break the unit down, clean, fit the new central bush and reassemble when my pbr order arrives and report back. Hope I made the right call with those springs...

#8 5 months ago

I used to do the same, thinking a new spring would be as good as a re-used one with a bit cut off but it often bit me on the bum so I now fit new as a matter of course. And 1mm is only a gnats cock out anyway so I wouldn't loose much sleep on it.

As for the wear, I stand to be corrected of course but I've got a few very old wood rail machines with very worn steppers where new bits just aren't available so I make do and mend best I can. Sure, sometimes they wont always reset to a correct start but hey, ho, they still work and add to the quirkiness of older games. [that's what I tell everyone ]

Keep going with it and see how you get on!

#9 5 months ago

Where this "wiggle" is going to come into play is on the adjustment of the run out switch. That is the leaf blade switch that rides on the outer edge of the bakelite cam. You need to make sure it remains closed at every step regardless of how much you wiggle the center shaft until it gets to the valley in the cam. If it opens during a collect cycle, it can cause weird scoring issues. Likewise, if your spider mount is too far away from the center bushing, your snow shoe contacts might not extend far enough to touch the rivet heads all the time. But you still want some in and out wiggle on the shaft so the hardware is not binding on either side of the bushing.

But, as others have stated, only 1mm of wiggle is not that much. I have seen much more on games like Hot/Big Shot and Grand Slam. Especially on Grand slam since every addition of a man on the bases makes it step a number of steps (that thing gets worked to death all game long). So, oddly enough, the metal on nylon "can" see some wear and tear over time. But it is fairly easy to replace. I am just not sure if Steve has stock of new ones. If you have to harvest a bushing, make sure it comes from a stepper that normally doesn't get a lot of action from each game. Probably the least used stepper I can think of would be a "Coin Unit" found on later model games instead of the use of 2nd, 3rd, and 4th player trip bank relays. It basically never moves when starting a game following a single player game. Only moves a little with 2, 3 or 4 players added for previous game.

Scan Style Bonus Steppers like Jack in the Box, Hot Shot, Grand Slam, and High Hand (which only rotate in one direction by the way) probably see the most use during each game. You also want to look for grooves worn in the ratchet arms by the teeth since that can cause problems too (especially noticeable on Roto Stepper arm parts).

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