Aargh...window frame frustration

[997at]

Hi All. Had my drivers door apart recently to readjust the window frame. At the front edge, there's a small trim piece that goes right at the lower front of the window frame where it meets the upper edge of the front door. It has a "hook" on the inside that fits underneath the inside rubber trim of the window and it's held in place at the front by a plastic push pin.
Mine broke when I tried to take it off. Ordered a new one. While waiting for the new one I reset my window frame and installed a new vapor barrier. Figured I'd just add the trim piece when it arrived. Fast forward to today...I'm pretty sure the trim piece needs to be installed while the window frame is out or loose cuz mine snapped while I was trying to force it into place. Oh well, tore the vapor barrier off and will order a new trim piece tomorrow. I'm planning on removing the window frame again to install this thing. Anyone have any experience with this little bugger?
By the way, for vapor barriers, 3M 90 spray adhesive is the Boss. It comes off perfectly clean when you pull the barrier off.