On my buddy's shee we we're riding ,took a break and he could not kick his shee over.The kick starter would not move.I thought the worse that the crank froze.BUT we pushed started the shee and ran just fine.He hammered it all day.With no problems at all.Weeks later he fired it up and didn't sound right.After a few rips around the yard it got worse.We broke the engine down and found three screws that hold the large gear to the clutch basket sheared.The bearings on the crank seem a little worn,but not locked up.
What could cause this??