We have an glow worm space saver that, altho old, is usually very reliable. In the past we have replaced pumps and thermocouple to keep it running smoothly but last week has been a nightmare. As soon as the weather turned the trouble started. We replaced the thermocouple and tested the pump - all working fine. The problem is that the boiler wont fire up consistently - makes all the right noises, clicks etc but switches itself off and on intermittently - even with the thermostat turned right up. We dont think the gas valve is stuck but it appears to be failing to stay open - if we tap the valve housing (gently of course) it comes back on - sometimes stays on for a couple of hours, some times stays on for only a few seconds - sometimes starts itself up. We have no insurance and no money to replace the boiler or pay massive call out/parts bills. Does anyone have any advice please.