I must admit I never got into the plastic moldings like they have today and must be a b_tch to work on them. As far as pulling the knife through the Urethane though. I always made sure the blade was sharp, slide the blade right between the urethane and uptight to the glass. Tilting the knife away from you about 15-20 degrees and it would cut through that like butter all the way around except for Fords. Those had to be cut from the top and sides then push the glass forward to cut the urethane across the bottom about 6-7" up from the bottom. Fiat's were a bastard to do. They were a glue in and the cheap bastards wouldn't put much on the glass so it was just a whisker from the pinch weld and the urethane they used was like cement. We used to put blankets inside the car and literally break the glass with a hammer and use a hammer and chisel to clean off the pinch weld.
