When Bob's trap door is up the ball will sometimes hit the open trap door and not drop down to be returned into play. I can see the pinball looking up the left loop stuck in the trap door. When the pin starts to cycle to locate the ball the pinball will drop with a thud and hit the bottom of the cabinet. Major pain to take out glass lift playfield, find ball in the bottom of the cabinet and return it to the game. Any advice? FYI I purchased the pin NIB from Jersey Jack