One of my three pumps won't prime up. All pumps and everything else was working fine in March. Turned back on in April and one pump won't prime. Air in the suction line to that pump. All filters have been cleaned. All seals are good. Pump motor is working fine. I suspect a broken or clogged suction line. I (and the local pool service company) filled the pump basket with water many, many times trying every combo of other 2 pumps on/off and can't get it to pull in water on the suction side. Motor is definitely working. Any ideas or suggestions?