I just looked back in my notes and another poster (sorry, I forget who) sent me this pm:
"I notice a few people had a cooling fan issues, a stick breaking the blades and the nightmare of trying to figure out how to replace it. Here is what you need to do. A friend of mine, who is an experienced heavy equipment mechanic helped me out.
First, we removed the parts that the arms of the MMM attach to (large gold bushings). Then we took apart the driveshaft by removing the split ring and knocking out the pin. Then we were able to access the fan, and remove the damaged one with a flexible ratchet and replace it with a new one. Then we put everything back together. It definitely helped to have my friend help out, he has the experience and appropriate tools to make the job easier. It took about an hour or so.
Also, keep in mind, these tractors, thought powerful for their size, are not a JD 650 dozer."
Hope that helps.