hi gasman reason pump didnt work was a faulty zone valve.it seems when heating was asked for it never switched over.replaced motor inside valve rather than change complete valve.pump back in action.many thanks for your assistance buetoon ps posted this answer in how it works by mistake then realised what i had done.when i could not find it on here
Glad you got it sorted blue tune. i did'nt think the pump was at fault and suspected external controls such as I suggested in C). I just did not know you had any zone valves fitted.