no central heating on systemate 2000

Hi my central heating has now decided to stop working after a difficult cold jan as i had to replace the middle pump and all the gate valves. Once repairs were done i found no power was getting to the c/h pump after a fiddle around with the settings the c/h decided to work all 3 green lights were on and the led "on" was working...great news....however as of last week, there is only 2 green lights on (bolier pump and dhw pump) ch pump light is off.
I have tried re-setting the whole thing but to no avail.If i turn on emergancy hotwater and c/h then it comes on(i.e bypass the system)...so any help on this one...my bolier is a gloworm micron as well but it is working fine and gets serviced every year.