Same Thing over here, I found out that the black strip on the outside of the window has "rock" type things inside of it (where it meets the window) and with age the edge opens up allowing these to come out and scratch the window as it goes up or down. I had to take the strip off and with a screwdriver scrape the inside to pull most of the rocks out. You can then use pliers to close the opening. Window seems to move smoother also, still left with previous scratches.
