I just did this job on my 51, with the deluxe trim. I know that the one piece is different but there are some common features. I laid mine against the frame and when the time came to pull the string, I lubed the pinch weld. I used KY Jelly and all joking aside, you couldn't get a better product for this. It doesn't stay a liquid for ever and mostly evaporates leaving a small sticky residue. I found that I had to keep checking if the window was centered in the frame etc. I would pull about an inch and then check. If the string is really hard to pull, usually the gasket is too far down from the lip and you can tear the rubber. If it is too easy to pull, the gasket is too high and it may slide off the lip. It is nice to have a backup plan in case the string pulls out ahead if the lip. This may be a second string or maybe proceeding from the other end. Also I started from the bottom and worked up. I figured if the window was a little high, I would have gravity working with me.
