Two things to try - first, re-bend the copper contact on the offending light bulb socket to provide more pressure on the bulb, plus clean it and the sheet metal areas where the bulb screws in.

If no dice, then pull out the lamp monitor module (in the fusebox on my 126) and open it up, re-solder all the connections from the PCB to the pins. All modules of this style tend to have solder joint issues on the pins. If yours is similar to the W126, it's a rectangular black box located in the main fusebox. It's roughly the size of a 3.5" hard drive. YMMV.

No grease should be necessary on the bulb (it will ooze everywhere from the heat) or on the Mercedes connectors (they are silvered and even silver oxide is VERY conductive).

I believe that on most MB of this age, the 'other end' of the wire is indeed the lamp monitor module.

__________________
-tp


1990 300SE "Corinne"- 145k daily driver - street modified differential - PARTING OUT OR SELLING SOON - PORTLAND OR. AREA - PM ME FOR DETAILS
1988 560SEL "Gunther"- 190K passes anything except a gas station
1997 S420 - 265k just bought it with a rebuilt trans. Lovely condition