Being a vert owner, I know it’s pretty much impossible to find unscratched glass for your door windows if yours are scratched because of worn out felt guides. It’s a big detractor from an otherwise nice looking car (if you’ve restored one).
I was surfing youtube and came across this video. They perform the job “on car” but I think for the vert glass you would need to remove it and put it on some foam rubber or something, to do the job.
Enjoy and I hope this helps someone. I’ll probably use it at some point.
If you can leave two black strips from the time you exit a corner until you have to brake for the next corner, then you have enough power.