Please help. I bought a used hammerhead 150 for my son who is battling a serious illness. The look on his face was awesome when I brought it home and he has been riding it off and on for about a week. Yesterday, the kart stopped shifting. It still runs, but will not shift into a higher gear. As you know, this is an automatic, and was working fine until yesterday. I have to get this going again, as it is great for my sons spirit, and he is no down again. Here is what I have done so far:
1. Checked the gear box fluid, drained it and refilled - no help
2. We have taken of the cover assy. and the belt looks very good.
3. We removed the nut from the outer clutch Assy (it was way difficult) and inspected the outer clutch (seems ok?)
4. tried to remove the nut from the cooling fan on the other end of the belt, but it is too tight and the whole thing turns (any ideas how to get it loose, and do I even need in that part?)

I am looking for anyone who can help steer me in the right direction. Please do not tell me to take it to a dealer, the company does not answer my e-mails. I do have a friend who works on ATV's and is quite good, but we need to know where to look.

Any help and advice would be greatly appreciated.
Thank you!
Doug