This is a dumb question, but I can't find an answer. Tried the local stealer, but all they saw was a chance to make some money.

On my '99 E430 there's what I think is a sensor unit (???) mounted on the windshield directly forward of the rear-view mirror. The thing has started rattling. I can push on it and the rattle stops, so there must be something loose inside. Simple problem, but its getting annoying.

Has anyone else had this problem? Is there anyway to pull the unit apart to troubleshoot it? Any help would be appreciated.