I do not have the car that is the subject of this thread but was wondering if it is possible to flush the torque converter by disconnecting the cooling return line to the transmission (if it has such a fitting), placing it in a suitable collection vessel and running the engine until ATF stops coming out?

I know this sounds scary, but this is the prescribed procedure to remove the fluid from Ford Taurus/Sable automatics and which I have done on my Taurus.

I don't know if the design of the Benz transmission system allows this approach.

On my Taurus, it makes a difference between getting 11 - 12 quarts out vs 4 qts by dropping the pan only.