hi can anyone help.i've just been to a call where the customer says they are only getting heat to the upstairs rads.i immediately thought a faulty pump but discovered the 3 port had been left in the manually open position.i put it back to normal and made a demand for heating,the lever moved over but not enough to hit the microswitch.as it was late in the evening i just dry wired a new 3 port in.the lever moved and made the microswitch but the pump failed to start and hence no ignition.the strange thing is with the old 3 port if i pushed the lever that bit further to make the microswitch the pump kicked in and the boiler fired.duff 3 port?????any ideas? would be a great help