I had one doing some crazy things like that, and it ended up being because I had fried one of the socketed buffer chips. I had a short into the switch matrix, from the solenoid that ran the spinning target on a Close Encounters.

Personally I would try emailing Ace, the gentleman that works on them with Ni-Wumpf... you can get the email off their website, he's incredibly helpful and ultimately can repair it for you inexpensively if it ends up being something on the board.