yes, it is the rheostat. amazing they want $85 for it.

i pulled it out and put it back it. interestingly the light go out when you tighten the screw really tight, but when loosen it comes on. so i put the rheostat back on but not as tight. let's see how long it lasts.

the contacts looked clean.

thanks guys. this has bothered me for months.

__________________
1990 Mercedes 300 SEL (320,000 miles)
1994 Mercedes E420 (140,000 miles)