Priming cap, thats what i have decided to call it. Anyway, i just recommended on a post how I had not had any probs with my CF canisters, then 30 minutes later my CF1000 gets an air leak that surges air into the tank via the spraybar. Have located the leak to the before mentioned screw in priming cap on the top of the power head next to the inlet/outlet taps. What is this really called, anyone else had the same problem & what you do to fix it?