Quoted from Mopar:
Most likely the ball count not always stepping up is from another area.
Not sure if you have a schematic, but you'll want to check the closed switches in the Extra Ball Relay,
an open make/break in the Outhole Relay, and an open switch in the Ball Index Relay.
(Could also be a closed switch in the 2nd Ball Relay and Score Motor B2 and D3, but seems not likely)..
The Ball Index Relay needs to be energized for the Ball Count to step up.
The Ball Index Relay energizes from a make/break in the Playfield Runway switch, (and also an open switch
in the 100-900 Relay)..
Once energized, it remains energized from a switch in the Ball Index Relay itself, and a closed make/break
in the Outhole Relay..
Hi all, just circling back on an issue I reached out about last year as I finally have a solution, and wanted to make sure it was noted in case anyone else has the same issue.
I had a problem for the last few years with my Sound Stage not counting every ball drained. After checking everything else dozens of times it turned out to be switch C3 on the score motor not being closed enough. I adjusted the gap as tight as possible without touching and this completely solved the issue. I would have never thought that would fix it, but sometimes you're looking for something so complicated you miss the simplest things.
Want to mention I wouldn't have figured this out without the folks from Lyons Arcade in Rock Hill, SC offering me guidance. I reached out to them after watching their CCM Gun Smoke repair video on their YouTube channel.