WOW - nice to see our first Tech problem on a Bally bingo !
I think there are tilts in the door, in the cabinet and their might be one in the head. The door would be the first place I would check. I could be wrong, but I think these had the glass tube with mercury (mercury switch). If that has moved, then the game will be in tilt mode.
I might have schematics for this game.
