Hi, I would be grateful if someone could help!! i have an apollo 30/50 boiler that has recently stopped working(pilot wont stay on). I have called my plumber in and he has gone though by process of elimination by replacing the thermocouple, gas valve & Overheat Cut-Off Device. The pilot light will only stay on if the pilot is removed form its location, when it is put back in its proper location it goes out???. It is serviced and tested every year by the same corgi plumber. (i have not touched or altered the boiler myself, i like my house and body parts where they are, i leave it to the corgis!). thanks in advance.