Neglected Plastic on Convertible Top - Help!
 

I recently picked up my first 986, and the previous owner completely neglected the plastic window on the convertible top. The cloth is fine, but the plastic is covered in mold, mildew, sap, etc. I've tried various cleaners (mold & mildew remover, hand sanitizer, Goo Gone, Windex), but it's still not cleaning and very hard to see through. Before using PlastX to polish the plastic I'm trying to remove all the build up thats on there.

Any unique ideas like steam cleaning (not sure if this would ruin or melt the plastic) or other chemicals to make it somewhat transparent for the meantime and before I consider replacing the whole top?