First off all thanks for all the old posts. I was able to get to this point with the help of many people on this forum. Ok so its a 1976 old chicago that I bought broken, but everything works except ball advance. Good condition machine from guy with other pinballs. I've cleaned and exercised all stepper units. Outhole counts down bonus and ejects ball at end of ball. I'm stuck on the ball index relay. Ball goes into play and the ball index relay pulls in as it should after scoring. If ball drains, everything from bonus to eject is normal. Ball in play just wont advance. Then if I put slight pressure on the relay stack, EVERYTHING works as it should. bonus countdown, ball eject and ball and player advance. I'm feeling like its solved. Switch on relay is dirty or not gapped correctly right? Ok so i gap them and clean them and it doesnt work. Then I verify that when the relay is pulled in that the N/O switches that are now closed are actually closed by putting meter on actual wire solder joints. They are verified closed. Solder is good. Tightened switch stack. The contact looks and works fine and the pad is not loose from the copper. Ok so there is the problem that I cant see out of the trees. If I dont put a little pressure on the switch it doesn't advance ball. Slight pressure and all is good. If I jumper said switch, then it all works fine, but then when I start next game with it still jumped, it starts on ball one and advances to ball two immediately maybe that's a clue to the aces on this board. I'm open to the most simple suggestions. Totally stumped and I have a little experience. I cant seem to get away from the ball index relay switch. In the middle of writing this, I decided to removed the possibility that it was the switch and changed it. Ok so the same thing, switch checks out 100% and if I put slightest pressure on relay plastic or even relay metal pull in, it works normally. Seems like a timing issue, if I delay the release of the relay then its all good. Where can I go next? I hate to mess with the SCM but it seems like I have a timing issue here. Thank you for any input or nudge in the right direction. Tom

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Thank you so much for posting, I will try it in the morning and report back. I kind of suspected that, but I'm nervous messing with the SCM unless I have to! Those switches are so hard to adjust. I'll poke around the site for best ways to do it.

Tom

Wow, I would say you really know your stuff. Thank you. One post and I am fixed!! After I gapped SCM 3A it started working and then I noticed it would advance ball count in single player but not multiple players and then I went to 4B and that was resolved also. Very impressive. I guess those lower switches get the most pressure from the wheel and go out of tolerance more frequently. I learned about EM's when I was a kid and after a 25 year break I'm back. Its all coming back to me. Thanks again.