After sitting unused for years the game powers up, sound works and attract mode runs, but it will not take credits, start a game or serve a ball.

Attract mode runs but no credits and no game start after storage: factory reset

Cause: The stored settings and audits were corrupted while the game sat. Bally 6803 games can look normal in attract mode with bad stored data.

Checks

• Check the MPU batteries, if fitted, and look for leakage damage on the board.

Fix

• Do the Bally 6803 factory reset (the '65' reset in the operator menu) to restore default settings.
• Replace weak or leaking batteries, or fit NVRAM, so it does not happen again.

Systems

• Bally 6803

Games

• Motordome

Related tips

• How to read the flashes on pre-1988 6803 games
• Nine-flash LED code meanings
• Game boots but will not take credits or start
• CPU never starts: check the reset line at U1 pin 6
• Nonsense adjustment values after a battery failure

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