Had some friends over last night and we played my Jackbot for like 5 hours. Then suddenly the right flipper shaft broke off. Not sure if it is called flipper shaft but its the metal rod that goes through the playfield I'm talking about. The metal snapped off inside the flipper bat plastic. The flipper did not touch any part of the PF, only the ball. Gonna replace it but I'm curious to know what caused the problem. Is it just because it was worn out and the metal had became weak from all the stress its under from flipping the balls? Is this a common failure?