I have short burst of air in my return jet, at a roughly 6 second interval. I have checked all of the connections on my Hayward Sandmaster and can't find a leak. I have taken the lid off the pump strainer, cleaned the basket, and lubricated it with the lube that was left with the pool for me. Jack's Multilube 327... assuming it was the right stuff. Due to the almost exact timing of the blast, and the amount of cavitation in the filter strainer, I suspected that it might be pulling air in through a whirlpool formed in the skimmer basket. I've interrupted this whirlpool both by slowing the water with my hand and introducing more water into the filter basket with a garden hose. It doesn't change the air burst at all. I'm assuming that this is a problem, and have become aware that it is abnormal through the search feature, but I think I've about exhausted the solutions that I've come across. About the only thing I haven't explored is the clamp holding the directional valve on the top of the filter, and actually replacing the O ring on the strainer basket. I believe it to be about 3 or 4 years-old. I want to make sure that I am not missing anything obvious.