Wisconsin Pinball

What would cause the scoring to be added wrong? Is it the scoring motor or the relays themselves?

Most likely a combination. If the contacts on the relay were too close and making contact when they weren't supposed to then you could get a higher score than intended. Same thing on the score motor contacts. You need to really pay attention when adjusting those contacts. Tolerances are very close. It's super easy to start adjusting contacts and make things worse

I would start by looking at a relay you know is adjusted properly. Observe the relay when it is in a state of rest paying attention to what contacts are normally open and normally closed. Then manually operate it with your finger and observe how each set of contacts changes. After you understand what changes occur then you can diagnose the relay in question by looking at it. If course dirty contacts can throw that theory out the window

Another tip - only adjust contacts at the base of the blade.

Also concerning the score reels - actuate the 10 point relay and watch the score reel in question, when it gets to 90 and rolls over to 0 there's a switch in the reel that actuates the 100 point relay which in turn actuate the corresponding score reel. So an error in the reels can cause some funky scoring also.

I'll have to take a look. I believe it to be the scoring motor, and I really don't like looking at that. There's a ton of contacts there. If and when I do adjust contacts, I adjust them at the base. I made a bender out of some steel at work kinda like the ones that they sell. Works like a charm.