In the case of windows
we usually just pull them out, clean up the surfaces and reinstall them with fresh RV putty tape. because it is fiberglass, we usually avoid using any kind of silicone sealant, it doesn't always stick well to fiberglass and will soon leak.
I don't know what your roof looks like. There are a few Predoms in Canada, but none that I know of in the U.S. Can you post some pictures?