I am having the same problem. I have removed the hinges to discover that the screws that hold them on are not tightening properly. It was hard to get them off becuase of this too, the thread seems in tact but they just dont screw properly anymore. Now i have them off i notice that the holes they are meant to go back into are obstructed on the inside of the metal frame. Not sure what to do next but would advise you NOT to remove the hinges!
Paul B, December 2012