I guess my best advise, to group as well as myself, is Do Not OverThink this stuff. The more I have learned about German cars the more I think it couldn't be this or that, wrong! The simplest of things, such as low fluid levels, can and do occur in MB and BMW and Audi and whatever. My 1990 300TE was not shifting properly and I mistakingly thought "it must be the shift lever", couldn't be the transmission fluid level was low, it's a Mercedes Benz...wrong....It was low on transmission fluid and after I reviewed the owners manual I paraphrase, "Check the transmission fluid frequently and especially prior to long trips", what I am saying via experience is
that these cars are simply cars and that's it. They are not without common maladies....dig....why would Mercedes instruct you to frequently check the transmission fluid level if they, themselves, didn't think the transmission might leak? How could that be? Think about that one....