I'm for one sick and tired of replacing boat trailer lights - and I've replaced 6 sets of lights - from all of the manufactures. My problem is not getting water into them - but the fact that I drive over rough roads regularly - like 30-50 miles of forest service dirt roads routinely with my fishing boat. I think the banging is killing the filaments in the bulb. WELL guess what - they now make LED LIGHTS for trailers! MAN are these great. I put a new set in - the complete light assembly - now I've stopped this problem! You can search - but check out http://www.buytruckstuff.com/ledlights.htm