I had the same issue with my 00, the plug definetly is a holding place for moisture. This tells me one thing, the rubber Plug cover is Crap, so I fixed it. I use a semi hard Silicone Very very Little just around the bottom flap that rests on the Valve case. or if you are nimple enough a very small bead around it. It is very easy to peel off and stops water / mud and such from gettin in there. Remember to clean the Ruber and the Case when changing the plug. you do not want it to build up.