Pascal gives great support i had the same issue on a game with a short in wiring .It sounds like the board could not drive coil 8 at game start .The board test fires all the coils before starting a game if you disconnect the coil it will give you the same error.Its possible there's a bad coil on your game or someone used on another game that had a short or bad coil and took out the drive transistor there should be some spares that were shipped with board

E-mail pascal he will walk you trough trouble shooting his boards . I have used 5 of them they all worked great .The only issue was a short in game wiring. That damaged board transistor . Also There should be a black and red wire that connects from the board to the speaker