I don't know how else to describe! It's the bulb that illuminates the red portion of the tach. Lately, when I hit a bump, it goes out, and then comes back on. I presume something is loose. Damn Bilstein HDs! Rattling my car apart!

What should I check? How the heck do I get in there?

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former: 83 300D, 97 C230, 93 400E

current: 08 C300 Luxury , 92 500SL

I would assume that the bulb is on its way out, since that's easier to fix and more likely to be the problem. Change them all while you have it out.