There's also a Motor 1A, a Motor 4A and all the switches on the Z1, Z2 and Z3 relays that are involved in reset. I'd be tempted to look at those Motor 1A and 4A switches to see if they're gapped too wide, not staying closed long enough to pull the score reel plungers all the way in. They're on the schematic between I-18 and I-19.

I had the same problem with a couple of mine resetting. Played and scored fine, but would not reset every time. To fix mine I just cleaned out the coil sleeve and plunger. They weren’t even that dirty but they reset fine now. If you try this let us know if it works.

Just for reference, normal scoring uses the end of stroke switch on the reel, which means the score relay won’t release until the plunger pulls all the way in. The reset circuit only uses pulses off the score motor, so there’s no feedback to make sure the score reel actually moved. I agree with the previous posts. You either have a poor contact or a shorter than usual score motor pulse is the reset path, or a slightly sticky reel that needs maximum “oomph” to get it to move.

It is interesting to see that the machine works very hard to overcome the issue and repeats the reset process until it makes it to zero. It shows a bit of self-correction even though there’s an issue.

Dave

What switches do the nine problematic score reels have in common? That might help identify the most likely culprit(s).

Excellent observation. I'd never put that together. The feedback during reset only needs to be the Runout or Zero Position switch. How many steps it takes to get there doesn't really matter. During scoring each step matters so the EOS switch is used. Very clever.

Glad we could help - have fun with the game!