I currently bought my brute force from a friend, it ran and drove perfectly fine unitl i starter going balls to the wall in some thick mud. Drove around the woods in high gear for acouple more miles when all of a sudden the rear end seemed to lock up. i got it home pull the rear diff apart seemed fine had a little water but that wasnt the problem. my bike still turns on it goes in to nuetral high and low gear with no problem, but when i try to put it in reverse it wont go. also i can see the driveshaft just a little bit put it in high gear gave a little throttle and nothing spins at all. what could this possibly be? its a 2012 brute force 300 2 wheeldrive with a 1000 miles on it.