My daughter's 84 300D has the same problem. When I push the switch forward to "brights" the headlights go off sometimes. When they go off, I can jiggle the switch and they will come back on. Feels like there is a weak spring in the switch. Do I have to replace the entire combination switch (which includes the cruise control switch) or can I clean, lube, and repair the headlight bright/dim part of the switch?

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Bruce

73 220D (never left Germany)
81 300D (totaled)
84 300D (Purchased '03, sold '17)
85 300SD (purchased 10/01/03)