Hi guys, I have an ongoing problem with mold growing in and on the white lap sealant that Itasca used on the roof of our class C RV around vents and such. The roof itself cleans up just fine. It's almost like a thin fiberglass roof (06 Navion). I have gotten so desperate that I have even tried diluted bleach directly on the sealant and a small toothbrush. On any other surface, bleach kills mold quickly but this sealant acts as if the mold is inside of it. Any ideas short of tearing up all of my sealant and replacing it? Everything else on the rig looks great except for the dang sealant.