Are you sure it is the mirrors? Our 190e was very noisy, on the driver's side. on examination, it was apparent that the top of the door was sprung out by about 1/8 inch. I confirmed that this was the source of the noise, by winding the window up onto a rag, so that I could pull on the rag and pull the top of the door inwards. The fix consisted of winding the window down, putting a knee in the middle of the door, and pulling in on the top of the door. After several tries, the fit of the seal at the top of the door looked like the passenger's door seal, and it was quiet. It seems a bit crude, but it worked.