So I just picked up a real nice Old Chicago. Got it fired up at home and immediatley ran into some issues. I read through a recent thread of the same issue here but everything I tried from that thread did not solve the problem. I do have the schematic and have been using it. So let's start by saying that I can't get any credits from depositing a quarter. In the meantime I've just been adding credits manually to the credit reel. So I push the play button and the game resets the scores (no matter how many players have scored, it resets all of them), it gets ready for the ball, but it does not kick it out. So I enter the ball manually. On the Old Chicago it scores everytime dropping down through the top lanes. That energizes the ball index relay, every time. All the scoring works good, the bonuses, etc. Now the ball drains. It closes the outhole switch (checked with DVM and cleaned), the bonus is added, score tallied, ball index relay shuts off, and thats it. The outhole relay never energizes, the ball count never advances. If I manually move the outhole relay the game advances and the ball count moves and if on multiplayer the player changes. I've gone through and cleaned all the switches on all the relays and discs and visually checked contact on all of them. This machine is really clean and it didn't need a whole lot of cleaning. Checked over the jones plugs, fuses, manually checked each circuit function (such as tilt, scoring, etc). My mind is boggled and I need a new direction to go. Please help!

Wow, you guys are good! It was a switch on the bonus unit, just enough out of adjustment. I adjusted it and it now kicks the ball out. Unfortunately, now I am not getting the ball count to advance. On to diagnose that.

Problem solved. When I cleaned all the switches yesterday, there was a switch on the extra ball relay (NC, between wire 14-2 R-G and wire 90-3 GRAY) that was physically working but not making a circuit. Ball and players now advance as normal. Again, thank you both wizardblom and rolf.