I have 6 stations for my backyard, they consist of Irritrol 2700 anti-siphon valves with filter attachments. I unscrewed one of the filter attachments and after I put it back on, this particular valve makes a loud humming noise when the valve is turned on. I called Irritrol and asked one of their support people what could be causing the noise, and he didn't have a clue. He sent me a replacement solenoid, thinking that might be the problem. It was the wrong solenoid though, but then I decided to ...