Well, I took a look at my window problem today. Turns out the main problem was somebody else owned the car before me and really didn't know what they where doing.
First issue:
This window didn't have a sleeve clip on it! It has four holes drilled around that area, and lots of glue or epoxy. Guessing this was a previous owner's attempt to fix the missing clip problem.... This causes problems for me because there is glue stuck on the back of the assembly which I can't see, but gets in the way of the clip, and I can't tell if the clip is the wrong size, and the glue is in the way.
After getting much of the glue off, I was able to get the clip to seat almost perfectly:
Fitment was very tight. I think if round some corners, fitment will be much easier. There are also a couple of very subtle chamfers on the original that I didn't include, these will also likely help improve the fitment.
I did test the window with the 3D printed clip in place and it worked perfectly.
Anyway, progress is being made, so YAY!.
I'll do a new version of the clip and test that one (hopefully tomorrow).
Cheers!
Ian.