1/4 glass installation on 68 Dart

I tried a couple things last night but no luck. I'll work on it again tonight. I'm going to try and put the mechanism all the way down as low as it will go...then put the glass in and see if I can get the rollers engaged. I know I'm making it harder then it has to be. The line workers did it hundreds of times a day in less that 3 minutes.