I suspect that the modulator pressure is too high. A large change should be tried to do some diagnosing. I would suggest two turns counter-clockwise. This takes about thirty seconds once on a lift.
If after this change you have shifts that flare while others are still firm then you have an internal problem. Its real concievable that you have a valve body problem.
From your technicians point of view its real hard to tell you, the customer, that a VB
replacement might be the best answer. MB makes rebuilt valve bodies that are fairly cheap (less than $400) for many models. They have many corrections built in that take care of idiosyncracies that were discovered over time.
replacement after a rebuild is often the only answer for shifting irregularities. It is hard to make a technical case against the tech in these matters although not so hard to make a legal case. The tech is supposed to know ahead of times the costs and risks and is then held to his attempt.
We do lots of MB transmissions and occasionally get burned but not often as any problem not absolutely diagnosable will include the provision that shift quality of the final product will only be an issue after a rebuilt MB VB
is installed. When these cases come up we loose as we wind up doing the VB
install for no extra labor as we are committed to one price for the whole job (which by this point has proven to need the VB
Boy, would I like to live in your neighborhood. I hardly ever see a customer that isn't interested in knowing the price.