I'm no expert, but had one years ago. I know they leak and have a habit of eating upper shaft bearings because it doesn't get a lot of oil. I would just pull the covers and take a look. If everything looks OK, reseal, and fill it with a good synthetic oil that will cling to the bearings and gears. and call it good. I don't know for sure of any special procedures, but shouldn't be any harder than rebuilding a manual trans, its all gears.
