Hi Steve.
I had the same problem as you, leaking gasket, and R&R the valve cover gasket using the procedure in the stickies by Bansai:
http://www.benzworld.org/forums/w21...0-egr-line-malfunction-error.html#post3908696
It was not difficult at all, just remove the torx screws (star shaped), and follow the directions.
I recommend that, when you have removed the valve cover, also clean the breather holes (just in case they are obstructed). Mine was obstructed and was the cause of white/blue smoke, that dissappears after the cleaning of the holes.
2 problems solved with 1 job
Regards,
Figu