I think I may have solved it. At least, it seems to be working now. There is another thread here somewhere that said that most people push in the center of the door to close it, and over time, the door gets bent. I had tried bending it the opposite direction after reading that post, but I guess I just didn't get it bent quite enough. After trying lithos plate solution with no good result, I decided to once again try bending the door in the opposite direction from what happens when you press on the center of the door to close it. So far, so good.