I just tore it apart and here's what I found:
The pinion on the end of the axle that goes into the wheel spins one direction freely. If turned the opposite direction, it should "catch" and lock into place. That's the way it's working on the wheel that spins on mine. The wheel that no longer spins doesn't "catch" regardless of which direction I turn it.
The way it looks like it's working is that pinion should "catch" the axle and then turn the gear box. I.E., I don't think it's the axle and gearbox not performing correctly, I think there's something wrong with the pinion mounted on the wheels end of the axle.
Here's a link to what I am talking about---look at number 4
https://homeownersolutions.toro.com/portal/server.pt?space=CommunityPage&cached=true&parentname=CommunityPage&parentid=1&in_hi_userid=77248&control=SetCommunity&CommunityID=221&PageID=230#drawingDiagramPage
Any thoughts on how to replace that, or if that's even the problem?
Thanks!
Shumax