Does anyone know what is under the cap of the CARC vent? Does the little top hat thing come off,if so is it a push fit or is it threaded? I am a little worried about water ingress after reading of a few problems on this forum,and want to investigate the vent,but obviously without damaging it.I thought about adding a peace of plastic to extend the hugger back a little,thus sheilding the vent from the back wheel.Any thoughts about this?