It might be the switch going bad in general. If you can grab one in the junkyard off of another w126 (even my 82 SDs have the switch) its worth the dollar and peace of mind.

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TC
Current stable:
- 2004 Mazda RALLYWANKEL
- 2007 Saturn sky redline
- 2004 Explorer...under surgery.

Past: 135i, GTI, 300E, 300SD, 300SD, Stealth