I have a Stuart turner pump in the garage which supplies the entire house hot and cold water . I have had pump serviced by a engineer as it was messing about , when you turned a tap on anywhere in the house it took maybe 3sec for the pump to kick in the once started it would run for maybe 3sec then off and on off and on very annoying ,it continued to do the same thing even after the service !!!!! If i hold a magnet to the sensors on the flow side off pump it works perfect , the sensors were also replaced but problem still occurs !!!!!!!!!does any one know what would be causing this ??????