Hi all, I have an old glow worm boiler 30 cxi that I need to re pressure after bleeding some rads. I looked on line and it said to turn the blue knob anti clock wise to fill and re tighten after when required bar pressure is reached. When I turn anti clock I can hear water, and it is dripping water from the other side of the boiler, but the digital display bar pressure is not going up at all, Can any one help please.