I have seen very few of these that were no good. My advise is to take it to a tech who is goooooood on Mercedes and has been in the buisness for a while. Then you will have a good base line to start from. Let them do a full service with valve adjustment and all.
Good luck

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Benzmac:
Donnie Drummonds
1992 500E (very soon I hope
1981 280GE SWB
ASE CERTIFIED MASTER AUTO TECHNICIAN
SERVICE MANAGER FOR 14 BAY FACILITY
MERCEDES SPECIALIST 8 YRS
PARTNER IN MERCEDESSHOP.COM