Bally Flip Flop. Insert coin, credit is added. Press start button activates Credit relay (switch contacts move). That's it. Game does not reset, GAME OVER remains on backglass. I can manually activate COIN relay, CREDIT relay, and RESET relay which will clear score wheels but game remains in Game Over. Will not kick out ball to shooter lane and nothing on playfield functions. If I manually energize Interlock relay LATCH coil, the game can be played. But the INTERLOCK relay does not hold at any point during startup. Neither the LATCH coil, nor the TRIP coil. They do not energize, they do not hold in order for the game to play.

Thanks. I do have the manual and schematic. I understand what is suppose to happen, but no idea why it is not.

Switch contacts clean and proper. Push start button, Reset relay moves (clicks) but nothing else. If I manually move Reset it will clear reels but still in Game Over. When I manually move Interlock relay switches, it will allow game play but will not hold. As soon as I let go of the switches, Game Over.

I'll check Score Motor switch 8F. Regarding the switches on the Interlock Latch relay, what is the 'normal' position of each switch? NO, NC. Maybe they need adjusting. Thanks for your help.

SCM Switch 8F was open. I closed it and now pushing start button resets but does not start game. I will check switches on Latch relay. What is the association with the M/B relay and the Interlock Latch relay?

Okay, adjusted switches on Interlock Latch accordingly. Now the relay energizes, but the Backglass still shows GAME OVER and the Latch will not stop energizing. Playfield is active as though the game was in normal play. But the game does not reset nor start when Start Button is pressed. I had to slip a index card between Latch switch blades to get it to de-energize, which also turned off the Game Over in backglass.