@Whitetail Hunter Welcome to the forum.
From part numbers looks to be the same booster used on other older Kubotas like the M4500DT so a few people including me would be interested in how you solve this. 2 thoughts:
1. Someone else at OTT posted that they overhauled one almost certainly like yours in the last few months I think, may be this year. Shouldn't be too hard to shake the tree and get them to let you know what they did.
2. Would you be willing to write up the job you do on it, including seal part numbers or sizes?