I would love an OnBeam to go with my Rocket III.

I'd try putting some replays on the replay unit by manually turning the wheel and see if the replay/credit button starts a game.

Oh that problem. Sometimes the key is hanging on the hook just inside the coin door, or it might have fallen off in transit and be knocking about inside the cab. Doesn't that machine have the lift up motorboard - could be under that too. I'd check everywhere inside before drilling shame to ruin original locks if you have them.