Yes to the silicone approach.
do some trial dry fitting to figure out your movements, as you don’t want smeared silicone all over the place. 😉
I used two small spring clamps for holding and maneuvering each strip.
I took strips of cardboard, folding about six of them into a V-shape, and then added small cardboard strips to form a proper width wedge to hold the strip in place and allow the silicone to dry. You will do this twice on each door …… don’t try to wedge two pieces on the same door at the same time
The upper few inches of window travel are a well known issue. I suggest you take out your U-channel felt and then notice how things change. I doubt you will discover you have a perfectly smooth and easy window even with the felt removed. The slightest adjustments to the two rubber cushioned bolts that attach the glass to the regulator will often find a sweet spot, or something much better. You can adjust the position of the rear window track, also.
Larry
