Our sliding door was installed a 4 years ago by builder when he converted our bathroom and toilet to a walk in shower room for my wife and is fine, works well. However every now and again the door seems to move on its fitting in that it doesn\’t close all the way, leaving a small gap between the door and the frame on the left that makes the surround. The door stops are in place at both ends and however the door stop on the left where the external part of the frame is does not engage before the door gets to it\’s closed position. I would have though that the door reaching the close position though before the runners run out would not be a factor though. Yet To fix I can move the door to the closed position or at least as far as it is at that point closing and the pull it to where it should be closing to. When I do this I can see what looks like the top hangers moving. I have tightened the 2 pair of bolts but do not want to go too far. Please advise on any adjustments, tightening procedures that my stop the door from moving.