I have 4 pocket doors in my house. 3 of them keep sliping out of adjustment. Each set of rollers have the screw with a adjustment bolt and a lever that is supposed to keep the bolt from turning once the door has been aligned. This does not seem to work. I tried "Lock Tight" on the threads of one of them, but it still moved out of alignment. These doors are about 5 years old. Do I need to replace the hardware or what? What makes them slide out of alignment? Help!