The lower channel fits onto the glass VERY tight with the filler material installed. I've always used the filler strip from Volvo--but don't know if it is still available. I've even used sheets of newspaper as a temporary filler. The channel on 140's was prone to rust away -- later, on 240's the channel is galvanized and what had been a common problem on 140's was no longer a problem. I've always removed the glass from the door (mark the location of the channel on the glass). Place the glass with the top edge on a wooden bench so you can hammer (carefully of course) the channel down onto the glass bottom edge (with the filler material folded over the glass--an assistant is very helpful here). On your '71 the aluminum frame unbolts making the glass removal easy. Later cars without the vent window and welded steel window frames require a little more juggling to get the glass out. -- Dave