I just bought a used 800 2008 sport and haven't even put 3mins on it. Sometimes and more often then not, when I put it into High thenc give it gas it revs up and then engages with a horrible clunk sound in the back end. Belts are fine and clutchs look clean. It will do it in adc 2x4 4x4 put not when put into low. It took me 10hrs to pick it up in the us and bring it back to Canada, it was fine when I put it on the trailer but did it when I pulled it off, didn't sleep that night. Any Ideas?