I have a craftsman snowblower 12 horse 33 inch cut, like ten years old it works great but wont propel itself all the time. Ive tightened up the spring that engages the clutch to the friction wheel. friction wheel looks fine. The belt looks fine as well. There was some grease on the clutch plate that ive wiped off. Every time I tinker with it, it will work for like 5 maybe 10 mins then stop propeling the unit. If i lift the wheels off the ground they spin but when i put i down nothing. Anyone else have similar issue???