Hey everybody. Thanks for the great site and all the helpful articles. I have been restoring a 1984 Bally Spy Hunter using all the information and links handily provided here in your various discussions. The information provided here has allowed me to troubleshoot, identify, and repair problems with displays, solenoids, - I've even made repairs to components on the pcb's with no prior experience in electronics.

After all of that work I still have one problem which I hope you may be able to help with.

The problem is this:
Ball shooter lane roll-over switch and associated lights.
For some reason, the lights test OK in test mode. I'm very careful to describe that the lights and switch function perfectly under test condition.
When game play begins - periodically, the game will simply place between 10 and 30 points on the scoreboard and behave as if the rollover switch had been activated (even though the ball has not yet been launched).
Obviously - the first thing I checked was the switch gap/contact point - this is OK. I also checked for any loose or nasty looking connections which might act like a switch. No problems were obvious under the playfield.
I'm wondering if this problem could be internal to the MPU?
Any troubleshooting suggestions?

Great Advice!!
I was just monkeying with it and came back to find your reply.
Perfect advice. Thank you!
The switch self-test showed a stuck playfield switch. The switch contacts were too close. Occasional vibrations would trigger the switch prior to ball launch thereby adding a bit to the score and spoiling the rollover feature.
Adjustment of the switch gap corrected the problem.

Thanks again for your reply.