I have recently moved house which has an old gloworm spacesaver F with no manual . It has been working ok until today.Now when is switched on there is a faint humming noise but it doesnt fire up .The pilot light is not lit and I cannot see any way to manually light it im assuming that it has an automatic light function. I have switched the room thermostat up to maximum so that it should be calling for heat . Has anyone any suggestion as to what the problem might be .