I have noticed with mine, the nut on the arm that lifts it tends to loosen after play. This will allow the door to gradually come out of alignment (ie not fully up) there is a switch that tells the machine if it is up/down, but often the door is somewhere in the middle and it never really knows where the door it.
This causes the door to sometimes constantly move, or get stuck up from time to time.
Pull out that PF and make sure your arm is in the right position and tightened real well.