At every switch-on the displays act as if the coin door advance button had been pressed (audit/adjust mode), and the game will not return to play.

Boots into audit mode every power-up with good batteries: bad 5101 RAM

Cause: The 5101 CMOS RAM on the CPU board that holds settings had failed. The batteries tested fine.

Checks

• Check the battery voltage and the holder for corrosion.
• Try the usual escape: with the coin door open, switch the game off and quickly back on. If it still comes up in audit mode, suspect the RAM.
• Look whether the 5101 is socketed; on many boards it is soldered in.

Fix

• Replace the 5101 RAM (or fit an NVRAM replacement in its place if the chip is socketed).

Systems

• Williams System 6 / 6A

Games

• Gorgar

Related tips

• System 6 won't boot and fails the 5101 RAM test even after replacing it: bad 5101 stock
• Leon's test EPROM fitted but the LEDs do not start flashing
• Game powers up in audit mode instead of attract mode
• Game keeps resetting: replace the 5101 RAM (an NVRAM works)
• Game always powers up in audit mode: bad 5101 memory chip
• Locks up when a second game is started: bad 5101 RAM
• 5101 RAM at U8 fails often; speed matters
• Two flashes only: U8 5101 RAM

Source: Pinball Repair help group!! (Facebook group)