My gas cap seems to leak from the seal by the threads. There is a rubber gasket in there but it dosen't seem to work. I've tried the stock little one-way valve inline breather on the hose. I've also tried just a breather hose. Both of these leak from the cap. What is that contraption under the cap? Is that some sore of one-way value? Should I take this out? Could this be the source of my problem?