the scuff marks ane normal friction wear and aging. When the plastic is really warm and soft when folding, a folding point can develop. sometimes a heatgun can resolve this, but not completely. Don't put heat gun tooclose to plastic. Also give the plastic a "karate chop" when top is about 1/2 way down so plastic is smoothe with no wrinkles. We get $525.00 to replace plastic window
