I have a 2011 Troy Bilt pony. It started feeling sluggish going uphill, then randomly wouldn't move when put in gear (a little shake seemed to get it moving, but could have just been coincidence). Now it won't move at all. I've followed the speed selector all the way back to the transmission, and everything seems to move as it should. The belts need replacing, but are still tight. The gear selector moves fine - it had some dirt around the pin going into the transmission, but clearing that didn't seem to result in additional travel. The drive pulley on top of the transmission will not move by hand in forward, neutral or reverse. Wheels spin in neutral, lock up in forward and reverse; and, off the ground, spin in opposite directions in forward and reverse. Any ideas?