Well, if the plug is intact then they didn't change the setting. The adjustment screw is accessed through the small hole in the air cleaner, takes a long 3mm allen, but the plug has to have been removed from the tower. Yes you should have an exhaust analyser to adjust, but one flat counter clockwise will lean it out a bit. Adjustments have to be made with the engine running.
'73 280SEL 4.5 (9/72)- RIP
Only 8,173 units built from 5/71 thru 11/72
'02 CLK320 Cabriolet - wifey's mid-life crisis
2012 VW Jetta Sportwagon TDI...at least its a diesel
Non illegitemae carborundum.