I have a Flojet pump used for presoak that keeps running (diaphragm keeps popping). I have changed the pump, checked for air or chemical leaks and did not locate any. It still dispenses product at the bay which seems okay. There are three pumps all six inches apart connected to the same air source. It is only the one pump with the problem. I also replaced the connection fittings. Honestly, I had two new pumps on the shelf so, it's the third pump that is doing the same thing. No big deal I just put them back on the shelf but does anybody know what the trouble might be?