The game does not start up, or restarts over and over.

CPU board will not boot, or keeps rebooting

Cause: The U11 one-shot on the CPU board has failed or is the wrong logic family; the board's timing depends on it.

Checks

• Read the marking on U11: it must be 74HC123AN, not 74LS123.

Fix

• Replace U11 with a 74HC123AN, in a socket.

Systems

• Gottlieb System 3

Related tips

• Game resets every two seconds
• Logic chips worth stocking
• U11 must be a 74HC123AN
• Gottlieb System 3 CPU passes test ROM, then watchdog trips: torn trace and wrong parts
• Reading the CPU board LED
• Reset capacitor workaround for boot garbage
• Nonsense message at boot, game stuck in a loop
• Booting a CPU board on the bench

Source: Repairing Gottlieb System 3 Electronic Pinball Games from 1989 to 1996, Clay Harrell (pinrepair.com)