The service manual (~$90) has a test procedure for the trac-lock. You raise one tire, and in neutral w/parking brake off, see how much torque to turn wheel. >30 lb-ft OK. In diagnositc section, only trac-lock problem is described as "chatter" when turning.
Also has info on replacing clutch pacs. Need to pull ring & pinion. Needs specialty tools. Not a backyard job.
You might consider getting a better locker that'll last longer if you're going to go through all that.
'98 White 5.9 ZJ, ASD's, Towing Package, 3.5" RE Lift, OME Shocks, Rusty's TC Skid, OME Steering Stab, MOPAR Steering Skid, 245-75/R16 Pirelli Scorpion A/T's on stock 16 x 7 wheels, Rusty's Front Tow Hooks, Kevin's Sliderz