well, turns out the the retaining device was no spring wire at all, like I thought.

So MBDoc, you may want to update your information file. Here is the flat
metal spring 'flap' which needs to be depressed to release the mirror cover for
face lifted models. I don't know how far this design extends into 211 models.
one arrow points to plastic catch molded into the housing. the other arrow
identifies the location to depress the metal catch.

Attached Thumbnails

   

__________________
-- raymond~
47º 34'N 122º 18'W