Not that I have the answer to your question, but I see you have a history of slipping in first gear. I guess I'm wondering why you want to pull the tranny, did you get it checked out by someone knowledgeable with MB trannies?
The piston for that band can be removed with the trans in the car. Replacement of the seal is simple & the band can be adjusted at the same time by measuring the clearance & replacing the "adjustment pin" with the corrected size.
Parts would be less than $20. Would take 2-3 hrs at knowledgable shop.