IIRC you have to split the case to replace the oil seal. It also wouldn't surprise me to see the axle bearings worn out. They're not really bearings, bushings actually. At that point you have a decision to make. Fix it or replace it. Those are great mowers and that 40" deck will cut better than any other Kubota mower to date once it's leveled, but parts are getting harder to find for the old T60 series, unfortunately. I think that transaxle was made by Hydrogear but I can't remember.
