I installed a system with Hunter PGM rotors last fall. Everything worked great this spring, but now I have 3 rotors that stopped rotating. I've taken them out and tried to clean them but they still won't rotate. I was just going to buy some replacements but found out that the PGM has been discontinued. I've tried to find a place to buy them, but everyone seems to be out. I have 2 questions. 1. Does anyone know where I can get 5 4" PGM's? 2. Would it be OK if I replaced them with Hunter PGJ's? Th...