In the process of replacing a leaking oil seal on the front wheel of my 4720H. Had it replaced last year also while still under warranty. The dealer gave me the seal, sleeve, and large o-ring - apparently $115 value??? - and I'm repairing it myself. So far the hardest part was removing and reinstalling the superstrength snap ring on the spindle - broke one set of snap ring pliers, bought another set but was unable to keep the ring from springing off while reinstalling it. Ended up grinding the tip of a set of 11" needle nose pliers to fit in the holes - worked like magic - should have thought of it first thing.
Another issue is the spindle nut, it's the kind that you take a punch to it and mash the edge into the slots on the spindle. I wasn't able to pry out the dent enough and used an impact driver to remove it. Buggered up the thread on the nut and don't have a tap the right size to clean it out and fix the threads. Off to the machine shop to see if they can fix it up. Why didn't Branson use a lock ear washer or a cotter pin and a castle nut?
Oh, there is also a set of shims between the inner bearing and the outer gear... .2T and .5T the .2T was broken and the .5T was worn...went to a machine shop and had the guy make a few shims for me between .6 and .8 , I figure one of the right size is better than 2 (I hope so anyway).