Sure do- the water seems to retain along the top edge of the unit. And over time gets in. My girlfriends dad has a caravan and uses the stuff called caraseal- specifically for caravans. it sets quite hard compared to silicone (and is less messy) whatever you use spread it across the join of the lens and the unit on the top and sides, and that should sort it. Its worked with mine so far. Dried the unit out with a hair drier first.....