I actually came to this thread to post some questions about my ball diff problems as well. I am running on a high-bite indoor carpet track right now. It ran fine for a while but it started barking. So I started slowly tightening it back up but it was still barking all the way to the point that I couldn't really tighten it anymore and I felt the "gritty" feeling you mentioned. I have heard a lot of people have these types of problems on carpet. Should I just stick with a gear diff for carpet and keep the ball diff for dirt? Or is there something I might be doing wrong with the ball diff? Will LOSA2954 work on this buggy? What oil should I start with?