My other project this morning was going to be simple -- pop off the rain sensor cover and install the new mounting pad/lens thingy to restore (hopefully) the rain-sensing wiper function. Looking through from the outside you can see the adhesive pad is all crooked and not uniformly stuck.

Silly me thinking that it would be no problem. Popping off the rain cover revealed two problems:

1) the retaining clips for the sensor were all broken; and
2) the sensor itself is adhered to the windshield somehow.

The glass is not original, but it is the appropriate St Gobain/Sekurit OEM replacement. At some point in between when I first saw photos of my car and when it was ultimately delivered the windshield was replaced. I suspect someone did a rushed job and hoped nobody would notice, but the M-B signature sticker had obviously been scraped off in a hurry and sloppily re-attached to the new glass. The seller denied all of this, unfortunately. Sigh.

Anyway I can order a replacement cover easily enough but I haven't yet removed the sensor from the glass as I'm wary of the various comments about the possibility of damaging a lens. Having no way to see the whole setup in its correct config, I'm not clear what the difference is between the sensor's lens and the little special pad which is normally stuck to the windshield.

FWIW I did purchase the March Adhesives RSP8, Rain Sensor Pad, and am operating on the expectation that I will basically remove any and all pads/adhesive from the inside of the glass, install my new one, mount the sensor in the clips of the new cover, and put everything back together.

But this lens thing, what is that exactly, and how does it interface with the pad on the glass?

Many thanks!