I'm posting this just in case it might help someone else: I have an older Toro Super Recycler II mower, rear drive. I was getting no power to the left wheel. After joining this forum and searching for answers, none seemed to fit my situation, though the problems described were similar. The forum suggested that the drive belt to the transmission may need to be replaced; mine was tight. The forum suggested that the gear in the left drive wheel may be trashed; mine was intact. Turning the axle on the left side (wheel removed) turned the axle on the right side in the opposite direction, so the differential was okay. So I replaced the pinion gears on the axles (both sides) and the little metal inserts (called rocking keys) that slide into the slots on the axles (both sides) and have a little finger that fits into the plastic bushing. Still no joy! Since the gear on the axle shaft turned freely, I wondered how the axle supplied power to the gear. Obviously, something had to engage one of the three slots in the axle (pinion) gear. So I took out the rocking key, scraped the crud out of the slot in the axle and the plastic bushing, reinserted the rocking key, then lifted it up into one of the slots in the axle gear with a small slot screwdriver and moved the axle. Wallah!! Drive to the axle! I lubricated the rocking key area with a light lubricant that allowed it to move freely. My mower now drives on both sides. Looking back, I probably did not have to replace the pinion gears nor the rocking keys, just to have cleaned and lubed them so the keys move freely up and down in the axle slots into the pinion gear slots to act as, for want of a better term, centrifugal clutches. Hope this helps somebody else.