I just fixed the same thing on my car. First check to make sure the rubber boots that cover the back of your bulbs are fitting snuggly. Then check the turn signals to see if the fittings are loose. Finally, if all else fails, get a tube of silicone with the little applicator, and put a fine bead of silicone along the seams of the housing where the lense cover meets up with it. It really doesn't take much to do the trick. A lot of times, the factory silicone sort of clumps more in certain spots than others, and the thin spots fail.