I got a John Deere LX255 and it was running smooth till it suddenly stop moving but the engine running still.I observed some unusual noise coming from the flywheel at the rear wheel that is attached by belt to the engine. The unit won't run forward or backward but the engine runs smooth. This unit is old and would like to fix it myself if its not complicated.

Hi,
The input sheave on top of the transaxle is splined internally and the trasaxle input shaft is spline externally. The splines of the sheave have stripped(they are meant to be the wearout point.
Peace,
Clarke