I've got a K-22 made in 1952. Yesterday I noticed that when the cylinder is pushed back into the frame, it sometimes rolls clockwise a bit without locking up. I looked at the bolt when this was happening and it looked like it wasn't coming up all the way. Then with the cylinder open I pressed down on the bolt and it seems pretty weak. Other times, it comes right up and locks up tight. Does the bolt have it's own spring, or a separate one? It this fairly easy to get to in order to fix it?