I have 4 pocket doors in my house. 3 of them keep sliding out of adjustment. These doors have the roller at the top with an adjustment screw and a lever that is supposed to lock in the adjustment. It does not work. I even tried "Lock Tight" on one door, that did not work either. Why do they continue to get out adjustment and what can I do to prevent it. Help! By the way these doors are just 5 years old.