Use your finger to step through the ball count step up unit. Do it multiple times and see if it ever skips more than one position or if it sometimes doesn't step up at all. Do it many times. It should step once for every push. If it works manually, it's not a physical problem with the ball step up. Then you have to look at what makes the ball step up fire (or misfire).

See schematic for switches involved in firing the Ball Count Step Up. Notice that it also goes through the player unit. It uses the player unit to determine when the ball unit needs to step up (after the last player). If the fingers on the Player Unit aren't lining up in the center of the rivets, all the way around, it could affect the ball count.

Don't give up. Tackle one problem at a time. Little victories.

Concentrating on your ball count problem, here is a section of schematic leading to your ball count step up. Missed steps could be any of these switches open. Double hits probably originate from the score motor or step units. This is the path that energizes your coil. The problem has to be with one of these circled switches or the Player Unit or Coin Unit.

It might be two problems. Jumper switches to try to eliminate the 'No step" then you'll just be down to finding what makes it double step.

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