300 SDL Gauges suddenly stopped working

Fuses are all ok. However, the buzzing noise is coming from a black box 1" x 3" in the fuse box which says 12V/2(4)x21W. I looked it up on mbz.org
and it says multi-function relay for blinker, hazard, wiper and rear window heater. Doesn't say anything about gauges.
Here again are the symptoms: all the gauges (oil, speed, temp) not working. Relay in fuse box is buzzing (blinker relay). Blinkers work and buzzing stops when signaling left or right turn. New radio installed last week (@ Circuit City), but symptoms appeared only several days after.
My guess is that the multi function relay is ok, but there is a short circuit somewhere causing it to buzz as well as causing the gauges not to work. I'll see my mechanic later this week but has anyone experienced similar problems? Thanks,
-- Jeff
snipped-for-privacy@mit.edu (jeff) wrote in message

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Before you change anything, open the fuse box and rotate each fuse about a half turn (these are the round bullet fuses in the copper holders). If this fixes your problem, replace them, and put a very slight coat of dielectric grease on the contact ends when you do.
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Fuse #6 was the culprit. Thanks folks, otherwise I would have first replaced the relay ($100 instead of $1.50).
-- Jeff
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