My first step would be to contact the shop that installed the replacement transmission, describe your findings and ask what the shop intends to do to make things right. Presuming the shop intends to do nothing, then stop doing business with that shop immediately. Hard to believe any shop would overfill a transmission by 2 quarts. There is a standard procedure for refilling a MB transmission that the shop personnel could easily have read online. Obviously that shop's personnel lack attention-to-detail. As I tell my sons regularly ... "just because a person earns their living doing something, does not mean he/she is competent."

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Fred Hoelzle