if you're talking about the permanently fixed cabin windows, the rubber seal you're saying is shrunk is just a cover for the frame screws inside. Remove the rubber cover, remove the screws and with a screwdriver or utility knife, cut through the caulk and remove the frame and glass....if you have the black stuff remove as much as possible mechanically, ie a razor or knife, and then clean up with some solvent....this stuff smears like crazy and black crap will be everywhere....clean it well and lay down a new bead of marine silicone made for windows and hatches....remember, there are two parts to caulk.....window glass to frame, and window frame to boat......the inside part of the frame holds the wood trim, so it will fall off when you remove the metal frame screws....when re-attaching, someone will need to be on the inside to line up the screws with the holes....once snugged up, the excess caulk will squeeze out...let it dry and trim clean.....now you have a leak free window.....you can probably get the trim from the dealer or maybe someone like Taco or Taylor.
