Hi. I posted earlier this year about this boiler and lack of hot water. The problem this time is that again, we have no hot water, but this time it appears to be because the top microswitch on the diverter valve assembly (S7) is not being switched on, or rather is very slow to operate when the water is turned on. This switch appears to be activated by the pump when it operates, and works fine when the heating is turned on, but not when the water is turned on. (I can see the switch moving fairly quickly for heating, but slowly for hot water). So any thoughts about the most likely cause of this please?