Slipping Diff

[Rocking Donkey]

I have recently rescued my old B2 from the purgatory of my parents garage. I’m having trouble with the diff slipping. If I tighten the diff as per the manual it is way too tight and if I tighten it to feel it slips! I have rebuilt it using associated grease and losi grease and have the same problem with both. I can tighten it until it stops slipping, but then it is way too tight. I think the problem might be the diff rings slipping? Any help would be much appreciated

Cheers

Ben