Sounds like you've tightened it up too much. Have you stripped the T nut?
If you've run it too tight, then you'll have likely worn the thrust race, and possibly scored the diff rings and maybe flatspotted the balls.
Rings can be flipped and or sanded, or replaced. Balls and thrust race can also be replaced. I'd crack it open to check if you have killed the t-nut or bolt.
I recon you've had your slipper far too tight, so the diff has taken the stress.
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