Answer to: only one drive wheel is spinningYou may have roasted the hydrostatic drive belt on that wheel
Answer to: mower deck will not engage when the PTO switch is turned on?I 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.