Hi Grant:
    Some of the guys on another list suggest drilling a small hole at
the top of the mirror, and then putting small lead shot inside, testing
the mirror until the vibration is acceptable.  These are for
motorcycles, where the buzz is pretty bad..........

Randy Bergum

Grant Holst wrote:

> I think I finally found the source of the buzzing
> in my dash. It's actually not in the dash, just sounded
> like it was coming from the center of the dash. It's
> the rear-view mirror. I was able to recreate the noise
> by revving the engine until the buzzing started. Then
> moved my head around the dash until I got close to the
> mirror. Tapped on the mirror and sounded very close
> to the annoying buzz that's been bugging me for months.
>
> Not sure how to fix the problem. Doesn't look like
> the mirror comes apart. Maybe some lead strips like
> you get with overhead fans to balance them?
>
> Grant