If this was 10 years ago i could have alot more info, but here is some things i remember (I think)
You can get to it after you take the rear PTO housing off. Use long studs in place of the bolts to make removal / assembly easier. It is heavy. Then if you have long small arms you can get to it around the carrier assembly. There are 3 different (I think) roller diameters availble, you need to do some measuring and math to get the right one and to get it adjusted correctly. I think i had the large one and just machined it down to where i needed it. While you are in there, inspect & clean the suction screen for the charge pump for potential wear on gears, brgs, and clutch packs.
Most importantly- make sure the park and gear shifter cables are free and adjusted correctly. I know because when i got mine it wasnt and a i put it in gear while it was still in park and heard the pawl break. It wasnt a good feeeling.
Mine was a open ROPs equiped one that was kinda rough. I spen a whole winter rebuilding my rear end and fixing up the tractor. I have alot of pride in mine and love love using it.