on my mate's hsp flying fish, one of the dogbones didn't sit far enough in the diff cup and caused all sorts of issues. i fixed it by a couple of 0.2mm shims on the inner wheel bearing side to move the dogbone closer to the diff cup, and a couple on the opposite diff bearing side, to move the entire diff 0.4mm over for a total of 0.8mm. after that, the dogbone sits nicely in the cup. and mesh still fine. the diffs for my vrx cars come with 5 shims, if you get them wrong the mesh can be too tight, and i guess usually its for adjusting mesh, but on this HSP, it really needed some shimming