sound to me like a broke locking hub or your locker is crap (most likely) the fix would be toss it and install an aussie or spartian locker. im not bashing your stuff but those lockers arent well known for holing up long due to soft metals.
78 j-truggy d60/14b,42's,tbi.
97 zj long armed and locked on 35's
03 quad cab 3500 ctd tow pig.