The Losi carbide ball diffs can be very touchy. If they are adjusted right and properly maintained, they work great. If, on the other hand, they loosen up, or are re-assembled wrong (grin), they can melt in a second. I forgot to put one of the washers in the thrust bearing, because I was in a hurry, and I melted the diff gear in under a minute. Rebuild your differential. The diff gear is only $3, and while you have it disassembled you will get a feel for how it works, and how important it is to keep it tight.