when you clean them you have to close the in and out levers, then unplug it. when you put it back you have to turn the in and out levers back, on then plug it in. if you do this differently it can cause problems. the filter has probably got some air in the in pipe and sucked this up and caused a "stutter" in the process, which has caused less suction in the water cycle and now you have air trapped in the filter. try shutting off the out lever and fill the filter manually at the top of the in pipe. if this fails, with the filter off, take the spraybar off and with the in and out lever in the on position suck on the end of the pipe that attacher's to the spraybar and when you have water coming up the pipe, reconnect the spraybar and turn the pump on at the plug