Thanks Patrick. That is actually very helpful. I decided to wait before proceeding till my garage is built. But first the road must go in, mud dry up and utilities mark for excavation. I will advise what happens in about a month or so hopefully!
You need remove top cover off rearend where the lift arms go . Under the seat . You can service the rear planetary from here .I don't think you need to split the tractor but it will be easier to work on if you do . You will see the fork moves the gear in and out of the planetary. This is where you'll find the trouble . It's just above the hydraulic pump.
Good luck . Also be aware that there are two different thicknesses available for that planetary. You may need to measure if you buy parts. But you should be able to tack weld the "gear" back in. Good luck.