[Danny McGee]

Im my opinion. It sounds like the doff just needs a rebuild with the new bits below;

Diff plates
Thrust race
possibily the balls too.

I very rarely have any problems with my diff and they usually last at least half a season before they need some tlc. Here's what i do (all new bits)

put a bit of grease (losi clear) in each of the holes for the diff balls, then pop the balls in using a pair of tweezers so not to get any other greases on them. Then i build up the trust race using the greyy/brown grease that comes with the kits. I put some on both the lower and the upper thrust plate but not a massive amount.

If you have the cr diff i also put some of that grease on the bronze rings as it helps it not slip.

I then bang it all together, possible adding a little bit more grease in the main gear (i dont put shed loads in though as its pointless) Then tightern it all up using a flat bladed screwdriver. I dont do it up tight at this point. Give it a few turns to make sure the grease is covering all the bits inside then tightern it up a bit more. I then install it in the car and set the diff by holding the slipper and making sure that the slipper "slips" first and not the diff. If its a new install you will need to crank it a little bit after the first run probably.

I think thats about it

Anything else feel free to ask

Danny