After installing a new pressure guage to a worcester240 bf combi I noticed that the pilot light had been extinguished. After several attempts to relight said pilot to no avail I fitted a new thermocouple. Still no joy. I contacted worcester tech to be told that a new gas valve is required. There are 3 wires from the overheat thermostat connected to the gas valve. If the overheat thermostat has operated can it be reset and if so how?