I just joined this forum because I ran across an old thread that described a problem very similar to what I'm having. I'm hoping that someone could point me in the right direction for the solution. I have a Gotleib Jet Spin. Here is what is going on. Several things weren't working well so I decided to go through the machine and clean everything thoroughly. I was very careful to disassemble, clean and reassemble every component. I had everything back together and turned on the machine and only the Game Over (Q), 1st Ball (U), and Tilt Hold (H) relays lock on. I double and triple checked every relay and switch in the entire game and all are clean and set up right. All switch blades are in the correct armature slots, making sure every contact makes or breaks like it should. Next I unplugged the top unit with the score reals, unplugged the game board, tilt switches and coin door to see if any of those were causing the problem. Essentially I have the bottom control board sitting outside by itself with nothing attached to it. I still have the same problem with those three relays. It's quite possible I overlooked something, but I can't figure out what. I did take apart the coin unit to clean it and I believe I put it back together right, but who knows. Could it be an issue there?

Thanks to those who replied to my question. I did dawn on me the next day the the game probably needed to be together in order to accurately troubleshoot it. I'm new at this, but I do have a decent background in electricity and mechanics. I finally found the problem. The one of the switches on the score motor was just making contact with one of the metal disks. I found it by poking around the switches with a continuity tester. I figured something had to be shorted because these relays would energize as soon as I turned on the power switch. After making a few minor adjustments everything started working, almost. I can't get the ball count to go past 1. I have a Bally machine as well and it has a stepper unit for the ball count. For the life of me, I can't find a similar unit on the Gotleib machine. I don't have a manual or schematic and I plan on getting them, but for now, how do I troubleshoot a ball count problem?

A special thanks to those who uploaded some pics. I think they will be very helpful. I played around with it today and figured out how the ball count works. Now with the picture of a piece of the schematic and the operating instruction I may be able to trace the circuit down to which switch is not working properly. I definitely will be getting a full copy of the schematics soon. Trying to troubleshoot without it is very challenging. I have cleaned and polished every switch contact and rivet in this entire machine thinking that should clear up any electrical issues. Since dirty switch contacts are no longer an issue, the problem is finding which switch is not behaving and that has me stymied because I really inspected every switch after I cleaned it to make sure it was set to open or close properly. It was labor intensive but I figured once I got it done I shouldn't have electrical problems for some time. So much for that idea! By the way, there are several relays that make a lot of buzzing noise when energized. I'm pretty sure that's a sign of a weak solenoid. Anyone with advice on that?

I should have been more specific. The buzzing solenoids are Q,U, and R in particular. These are to relays in the bottom of the unit. Using the circuit diagram and the operating instruction someone provided I was able to trace the entire circuit and there are no problems with any of the switches, so I'm left with nothing other than these solenoids that maybe causing poor connections. I can get the player and ball count to work intermittently with no consistency. I'll have only one player up and when the ball drops back down it may advance to player 3 or to ball 2, random stuff that sort of thing, which could all be related to weak of fuzzy connections causing the motor to over-run. Literally, I can't find anything wrong with the switches/wiring. I'm going to next pull out one of the solenoids and do and Ohm's check and see what it is. If anyone has dealt with similar issues and has any advice, I'd be grateful to hear from you. Thanks.

Thanks for everyone's help. The issues I'm finding now are switches that just need adjustment. I've been fixing them and clearing up some of the problems, but this problem with the ball count unit continues to elude me. I will check more switches later, but being I don't have schematics yet, does anyone know where to find P4F, P3F and P2F? Are they associated with the P relay? I have checked many switches with a continuity tester, however that can be tricky interpreting the reading when current can flow back through another closed switch to the other side of the switch I'm testing. I ran across a website with a lot of great information on repairing EM machines. There is a section on converting these noisy relays from AC to DC using diodes. This sounds like a good idea and it's supposed to quiet the buzzing. They may not be related to the problem I'm having, but I have almost everything else fixed at this point. I'm sure I'll get there eventually. This has been a great learning experience.