Ok, I know this is an old thread but I finished the restoration on the 67 coupe, gave it to my son and just noticed a dent on the front of the door. Somehow the spring "disappeared". How the hell that happens is beyond me but the thing was new. Anyway, I just did the wire technique and I couldn't get it to stay on opposite sides. Even when I had it compressed you would loosen it up and WHAM...it would slide over every time. Finally, I compressed it as far as I could on one side and used a flat head screw driver and a few curse words and got that thing in.
That sucked, to say the least.
Bought two in case I have to do this again...but I hope I don't.