Here is what I would do if I were in your shoes...

Weather you like it or not. You will into the first half of the transmission, and i would replace the frictions, and put new seals. Size-up the frictions to the correct gap, but really for your mileage, and what your about to do. It is a no-brainer to rebuild this your self. The 722.6 is easiest to do first DIY tranny rebuild. You would be $300 or so into the rebuild kit, and $50 into one bonded piston. Oh, $50 bucks into the the front bearings.

I'm going to rebuild my E320 4Matic at 180kmiles as my rear engine seal is leaking.

I have not done a DIY on this as I have 800 or so pictures from one rebuild showing blow by blow.

I have all the literature and pictures, and it would fit on a 16gig thumb drive if you want it. Just mail me a thumb drive, and I can load all the info..

A friend is going through the rebuild, and the service manuals are up on the site here on this thread. I think it is on Post 36

722.6 slip and shudder in D and R, rattly noise in N and P problem on 1998 S420. - Mercedes-Benz Forum



Notice, the last picture on post 27 is the front of where the pump mates-up. Mine has a few little pits on left and right, but I have seen them very pitted...

Hope it helps,

Martin