Followed by hinge pin/ball being worn or aluminum hinge itself being worn. Both replaceable parts from Scamp
. Call and have them use the post office to send. Bunch cheaper than the web store for small items.
The bottom corner of the door opening on the hinge side is attached to the frame by a small piece of plywood that extends a cross piece of the frame out to where the bottom of the door opening is. That piece can rot which allows the hinge side of shell to move.
Symptom would be door opening is wider at bottom than at top and hinge side of the door opening is not straight up and down (90 degree from floor) when checked with a carpenters framing square.
I would start with loosening the hinge attachment bolts and re-adjust as suggested. Check the other stuff if problem remains.