To avoid confusion, the multiplier lights are changed by a stepper or step unit, not a motor. The schematic doesn't show any repeating positions so it's possible that your stepper isn't advancing reliably. If you manually push in the stepper's solenoid plunger all the way and let it go, the stepper should step cleanly to the next position every time using only the power of the stretched spring(s). The wipers should come to rest at the center of the contacts below. Try this a bunch of times. You might see that every other time the stepper has trouble getting past the 7th position. There could be a small burr or other mechanical issue keeping it from sliding on to the next position.

/Mark

I'd try again. The board and those contacts should be shiny with no black streaks across them. You might try in this order:
- a rag with mineral spirits to remove any old grease or lube
- a rag with Novus 2 and some elbow grease
- a rag with some metal polish and more elbow grease
- if necessary, move up to a scotch brite or similar plastic cleaning pad

Also check the snow shoe wipers. They need to be shiny too and moving easily up and down in their sleeves.

What's going on with the contact board in the oval you drew? Is that dirt or some kind of damage?

Are the gear and the various stepper arms on the other side clean and moving freely? Does the gear shaft and sleeve need to be cleaned?

As a last resort, you might need a tiny bit of synthetic grease on the contact board. Cleaned steppers can usually work without it but occasionally lube helps overcome that last bit of friction that you can't chase out in other ways. Lube should be the last step though, not the first. Wipe on a tiny bit and wipe most of it off again.

You may need to slightly adjust the wiper fingers to put a bit more tension on the contacts (in addition to what Mark says above).

That is strange, I wonder if the wiper plate is in the wrong position - the three screws in elongated holes allow for adjustment. It may be worth adjusting the plate to see if you get correct operation, make sure the wipers are aligned with the rivets on the plate. You can mark the current position so you know where to go back to if there is no improvement.

Regards, Richard

Much better - cleanliness wise.

Watching the videos again I noticed that the stepper is always stepping even though the light isn't advancing. I had overlooked that before. I also notice now that there is a set of contacts among those you circled that has no solder lug or wire soldered to it. Given those two there's another possibility.

Since there are 7 lights the stepper has to take 7 steps to sweep through all of them. I think this stepper only advances and doesn't ever reset. So that means that there would need to be some multiple of 7 steps (7, 14, 21, 28, etc.) to get all the way around the contact board. I bet Gottlieb didn't make a stepper with a multiple of 7 steps. They probably did make one with a multiple of 15 steps though (15, 30, or 45 steps). So rather than making a special gear just for Sky Jump they may have wired an extra contact to the 7th position every other set to make a total of 15 steps (1-7, 1-7, plus an extra 7). Then they could use a more common stepper gear. So how many contacts are there in any given contact ring? Is it a multiple of 15?

The schematic doesn't show this, probably because only every other 7th position takes up two steps.

You could test this theory by checking the unwired contacts to see if they're wired to their neighbors.

So maybe you didn't need to do the extra cleaning, but no harm, no foul, and I bet it will run longer before the next issue now.

I think Mark has cracked it - I've just had a look at my Sky Jump and it does exactly the same as yours, something I had never noticed before, so I believe yours is working correctly and I've learned something!