I have replaced the bushing in the axle on my older TO35.
The main pin came out easy on my tractor, but I could see it being stuck inside the bracket would be a major problem.
Might spray the bolt with a good grade of penetrating oil for a few days before you attempt to take it apart.
If the bushing is so worn that the pin has worn into the cross axle, I would replace the axle.
Welding, heating the axle could weaken the axle.