My plastic rear window has some scratches that I would like to remove. I have tried the Meguire products with no success. How much pressure should I use to buff out the window? I was doing it by hand with no effect. Did not want to push on the window too hard. The scratches are light and according to Meguires, it should take them out. I had no scrathces until I put the new top down for a number of days to enjoy the weather here in the Phoenix area. I do put rolled up towels in the window to keep it from creasing.