I have been to a 12/14 Worcester heatslave combi where the radiators are heating with heating off and h/w on - I assume this is the diverter valve - the lever on the side of the actuator rises when h/w is called for but stays at the bottom when heating is called for - Is the actuator operating correctly or should the lever rise when calling for heating? How should the parts inside the actual diverter valve move to check not siezed i.e up and down/rotate? What should I check first - also cant find a part no for the actual valve. Thanks for reading.