I was using my wraith, and attempted to crawl up the stairs. I tried to go up the final step in the corner, then I noticed I was fully accelerating and my truck was not moving. I lifted up my truck to place it again because I thought I was using a bad line, then smelt a really bad smell. I placed down my truck, and gave it a little acceleration. It sounded kind of like the slipper clutch. I took it inside and let it rest for I while. I then took it outside and crawled around for about 5 minutes. The "slipper clutch sound" is really faint now. It it safe to keep using the motor? Or should I replace it?