I'm having trouble installing the front quarter windows. The bodyshop took the doors apart without me seeing how they are assembled. The third fixation point at the base of the door - I can see the channel below that should bolt to the base of the long vertical channel. An M6 bolt head fits into the channel but spins with no way to fix. An M8 is too big. I presume there's supposed to be a captive bolt or something similar (like a small square with a bolt). What should be there? And given that the bodyshop has snapped off most of the other captive bolts off inside the door I'm open to suggestions for replacements...
(here's the channel which supposedly houses the captive bolt in the base of the door
