My sled of 2 years always did it and this year finally had the clutch professionally rebuilt completely . It still does it even with a new belt. Ya I know hoist it up start it that way and move the track some before letting it down break the skis loose ect. I did all that and even after it had the track spinning freely for some time needed 5000RPM's to get moving. The belt was smoking some too. After that all is well just like before. The PO is a friend of mine and never had anything like that happen. When I had the clutch rebuilt a month ago I even had the guy check all the undercarriage in his shop. IS THERE ANYTHING DOWN THERE OUT OF THE ORDINARY THAT COULD DO THIS??? I burned a belt last winter because of that and don't feel like burning another.