The game boots and plays, and the adjustments menu shows the settings were changed ('factory altered', free play on), but in play it counts credits down as if not on free play and every game sets a new high score whatever the score.

Free play and high scores act as if memory resets every game: do a factory reset

Cause: The settings data in the NVRAM had become corrupted. The chip itself was fine.

Checks

• Reseat the NVRAM and make sure it is the right type and orientation.

Fix

• Run the factory reset from the adjustments menu (select it, choose yes, and press advance once more), then set the game up again. Replace the NVRAM only if the fault comes back.

Systems

• Data East CPU Version 3

Games

• Robocop

Related tips

• Combining two-chip CPU code into one 27512 for 5C
• Battery voltage at the RAM but memory still lost
• New CPU board locks up when the coin door buttons are plugged in: reseat the PIA
• Full CPU jumper settings by board version
• CPU still will not boot after the basics
• Free-running the CPU to check address lines
• One PIA output does not toggle under the test EPROM
• Coil passes every test but still will not work in play

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