I have a 2003 Polaris 700 classic with just 609 miles, and I when I hit the button for reverse, it kicks out, goes into reverse, and the reverse light flashes, but when I throttle it up, it won't move, and it just smells like it's burning the belt off of it. If I lift the back, the track will move in reverse, but the minute I put it down, and there is any sort of load on it, it will not move. Does anyone know what might be wrong with it? I would appreciate any and all help. Thank you in advance.