Originally Posted by rhodes2010

What year 300SD ?
The 1983 has wires connected.
I know 85 has plug on connectors, maybe 84 too.

But before that... I just opened and repaired mine with some contact cleaner
and small file (or sandpaper).

To take off the door panel is not hard.

Remove the piece of trim in the window/doorframe.
Lift the door panel out from the door. Earlier Benz use clips
that pop out, you pry the panel away from the door.
Not the 300SD, if you pry or pull it will break the not replaceable clips.
Lift.