The polycarbonate ports on my Pearson 27 were clouded over and actually appeared to have ripples in the plastic from the outside. They appeared to need replacement if I was ever going to see clearly through them again. I removed the opening portions and wet-sanded the exterior surfaces (utilizing a palm sander with a water spritzer bottle - but I can't recommend this unless you have an air-powered one). I used 1200 grit wet or dry and then used a product called "Flitz" with a buffing ball mounted in my drill press at 1950 RPM. The result is great!! They look nearly brand new.