This is likely a communication issue with the driver board. Ensure that the parallel cable from the computer to the driver board is connected and fully seated at all connector points.

Depending on when the game was made, there may be an interconnect that the parallel cable goes through at the back of the head. Ensure everything is solid there as well.

Replace with a known good parallel cable if all connections are good.

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Rob Anthony
Pinball Classics
http://LockWhenLit.com
Quality Board Work - In Home Service
borygard at gmail dot com