You might give Schmitt Automotive a call, they are a small independant shop in Bellevue. He is factory trained by Mercedes.

I used them for a vehicle inspection last year and was pleased with the service.

Sorry about the long URL, http://yp.yahoo.com/py/ypMap.py?Pyt=Typ&tab=B2C&tuid=12043023&ycat=7844597&city=Bellevue&state=WA&country=us&slt=47.610600&sln=-122.199501&cs=4.

Ross