When I opened my gun safe tonight the turn felt "heavy". Since it didn't feel right I was hesitant to lock it back. With the door open I turned the handle to the "locked" position and again it felt heavy...stiff. A few more turns back and forth and it's about locked up completely. It is really difficult to turn the handle...I've no idea where to start on this problem. A quick google search on the make and model produced nothing. Any thoughts on what might make the handle difficult to turn?