I have several Hunter PGP rotors that have developed leaks between the Pop-up Body and the Body Cap. I noticed on the Hunter drawing that there is a Seal Replacement Kit available. Is the kit a.) likely to fix my problem?; b.) worth the effort compared to just replacing the entire assembly?; c.) is the kit available? I am also curious why I have several of these rotors leaking and if it's due to the relatively cold winter (in Houston, not Minnesota)? The house/sprinkler system is about five year...