I have seen this problem before and the seat back was out of time. The seat back adjuster has two gears at either end and one was ahead of the other. How it got this way was a mystery. I took out the seat and layed it upside down. Then a took apart the gears and clocked it correctly. It worked fine.

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Benzmac:
ASE CERTIFIED MASTER AUTO TECHNICIAN
LEAD TECHNICIAN FOR 14 BAY FACILITY
MERCEDES SPECIALIST 8 YRS
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