system diaphragm could be shot or pin stuck keeping microswitch made. if you remove front panel and drop control panel down look to the left hand side. there is a brass assembly with 2 round brass housings with microswitches on them. the brass saucer shape facing you is dhw diaphragm, the one lying flat facing up is pump proven diaphragm, see if the pin is stuck out keeping microswitch made.
iain, June 2008
