Of cousre its not rocket science... I was making sure I had the wrong stop... that I wasnt using the wrong cable housing. I have the wrong part... now need to try to find the right stop.
That's annoying.
Aliexpress is full of different versions of cable stop inserts. Not sure whether all these will fit this frame, though. But the clip in variants should work?
Also, somebody in this thread posted a 3d-print-file for exactly this part. Try and look it up. That might be the quickest solution for you.