I think this should be simple fix, but the correct solution has eluded me. Searching tips to clean the fixed Catalina-brand--defining above-deck portlights has proved fruitless so far. I have accumulated white-ish stuff on the outside surface of the portlights. Not knowing exactly what they are made of, I have not been very aggressive in trying to get it off, but it is the next cosmetic project I'd like to tackle. I don't want to cause a chemical reaction that cracks or scratches or clouds the lens, or eats through the caulk. Assuming I'm not alone in this, please let me know what solutions work?