I did have a similar issue with the score motor, and checking with my old notes, it was a timing issue on the 50 points awarded when rolling over a top inlane. From what I remember, it was an adjustment on the first bank of score motor switches. The motor was not enabled for the 10 point relay to activate 5 times. It only activated 4 times. I can't recall exactly what set of contacts, but it was a simple fix, but hard to locate.
Report back with any updates. Aces High is an awesome player.