"only one drive wheel is spinning"에 답변You may have roasted the hydrostatic drive belt on that wheel
"mower deck will not engage when the PTO switch is turned on?"에 답변I had the same problem... I found one of the wires had rubbed of the plastic coating near the clutch and was grounding out. I put a shrink wrap tube on it and rerouted the wire from where it was rubbing. Haven't had a problem since.