I have some bad seals after fixing my water damage and some gaps are now 1/4 inch bigger even where the seal is still there. The seal doesn't seem very high end in the first place (1993 towlite). So what about vinyl base board moulding or maybe a garage door weatherstrip attached to the bottom lip of the top half? You wouldn't have to separate the 1/2s to install it and the price on the baseboard is pretty low.