After 13 years of ownership I finally figured out how the water gets in my driver's side headlight. The water flows across the hood and into the seam with the fender, along the seam to the tab that holds the headlight, down through the hole, on to the side of the headlight, to the side cover, past the crappy gasket, and into the headlight. For the fix. I dremeled off a couple of little lumps that kept the cover from sitting flush and ran a bead of hot glue around the back side of the gasket so it would have more crush when compressed. Here's hoping.