Man ya know on second thought if you are asking for help on doing a little job on this tractor I think you need to find a tractor mechanic to do this for you. It seems that you will be getting over your head. Sorry but I think you would be better off.
Could be a major job. I'd be a bit intimidated by it. Sure seems like you should be able to adjust it so that it would disengage though. If it were slipping, that would indicate replacement time.