Take it off and clean it out before you put it back on. I think I used something like WD40 to clean it out. Watch out though, it will shoot out all kinds of black junk. Kind of like carbon powder. Wrap the whole thing up in a rag before you shoot the WD40 to it.

-Jim

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1995 S350D, Green with black leather interior.
Bought January 2008 w/ 233,xxx miles.
I did 22,000 miles during the first year of ownership.