Failure around 37th tank with my build. I got a nasty scratchy sound when trying to restarting the saw, thought I had finally killed the all Farmertec build! First thought was the piston, broken crank, disintegrated bearings, dislodged circlip or broken rings. Surprisingly it was one of the springs on the clutch that broke at the hook. So ... clutch springs may be another part to watch out for.