I HAVE ABOVE MENTIONED BOILER WHICH IS COMING ON NINE YEARS OLD AND TODAY HAS STARTED GIVING ME A PROBLEM , WHICH IS WHEN EITHER CENTRAL HEATING OR WATER HEATER COMES ON BOILER FIRES UP FOR A FEW SECONDS THEN GOES OUT AND A FEW SECONDS LATER SMALL BUTTON UNDERNEATH POPS OUT WHICH I TAKE TO BE A...