My parents central heating system is a fully pumped system with a 3-port motorised valve controlling the CH and hot water from a hot water cylinder. We have recently changed the motorised valve motor due to no hot water. but still no hot water. The valve operates when the CH is switched on and moves the lever on the valve body but when the hot water is turned on the lever does not move and no hot water will come from the tap. Could the valve need replacing or are we missing something.