I've had a Yaki Road Shower for a few years, used pretty regularly, but last weekend it wouldn't hold pressure, was leaking through the cap - past the threaded part, not the pressure relief valve. I looked at it an there's no seal (rubber, plastic, etc.) on either the cap or on the "base" on the tank where the cap lands. Is there supposed to be? Gotta admit it's not something I've ever noticed before. So - if anyone here has one, can you tell me if yours has any kind of seal on it?