I have used a sealant, kind of like caulk that is flexible, yet adhesive and is waterproof. I have used it on many things from rusted out roofs, hols in metal, and various other products. Another good thing is that it usually comes in a variety of colors, to lessen visibility. Gasket sealer might seem like an obvious choice, but the down side to that is it gets rock hard, though waterproof, but is hard as hell to correct a mistake with it and ro replace anything connected to it---> forget it!!!!