I made a small video tutorial on how to take apart the legendary Carl Zeiss Pancolar 80 f1.8 and de-click it for smooth iris control and re-lube it for even smoother focusing.
My goal was to make this lens a workhorse for my video productions.
Exactly the same procedure also works with:
Zeiss Pancolar 50 1.8
Zeiss Flektogon 35 2.8
Zeiss Flektogon 35 2.4
Zeiss Sonnar 135 3.5
Zeiss Sonnar 200 2.8
Zeiss Flektogon 20 4.0
and probably others too, I've just done those.
In the end I bought step-up rings so all of them have the same front diameter.
So if you ever though of doing that yourself: it's pretty easy.