Did a bit of research and this lawn tractor has some version of the Tuff Torq K46. It looks as if a rebuild is possible by going through Tuff Torg for parts. I am just not sure it would be worth it to rebuild it until it fails. it has 480+ hours on it and I do see any reason to tear it apart until it doesn't move. Only problem will be that will be in the middle of cutting grass.
If any body has preformed service on these please let me know how it went for you.
If any body has preformed service on these please let me know how it went for you.