My 1994 E420 has a persistent rattle coming from the rear view mirror. It jiggles a little bit as I travel over broken pavement. I could not see any visible screws, but notice that the housing where it connects to the roof is rubber and probably removable. Rather than just pry at it until I break it, I figured it would be best to ask for some help. Is there a way to tighten the mirror back up? Thanks.