the rubber gasket on the top side is no good most likely. i had the same problem .what i did is un screw the top and inside and take the hole thing off.. make sure the core is not wet . if it is get it out and cut wood to fit the rot that came out . wgen you put it back together put a bead of silicone around the top side and put a new gasket under the top side (i used window foam )
