Mk1 - How to remove window frame?

I need to rebuild the window lift and replace the channel felt… Can someone give me an idea how to remove the frame? I’ve seen how the Mk2 frame is removed, but of course the Mk1 is different.

The felt will come off in 3 parts: two straight u-channels, held with a bolt down in the door body, with clips to the door thin part and one flexible - upper piece, clipped + bolted.
Clips are spring type, You’ll have to fight them (force withdraw the u-channel from them).
At the front of flexible u-channel - where triangular window begins - there is probably a screw hidden instead of a clip. Have a look at these pictures: (LHD driver’s door).

Did You find a source for this u-channel / parts? I failed …

Wow, great pictures…I have not found replacement, but was going to pull everything out and take it to some trim shops. But I also have a problem with the linkage and was hoping pull out the complete mechanism. By your pictures, it looks like the first step would be to pull out the glass. Not sure what would be next. Jeff S.

The lifting mechanisms are actually separate parts, with a single roller wheel in the channel attached to glass. I don’t know - but maybe You could remove the mechanism with the glass still in. See pics: