Same problem.
A single plastic pipe clip for 15mm copper tube fits ideally in the recess above the boiler thermostat knob. This holds the knob assembly down so that you do not have to press down on it to stay lit up. This does not cure the problem completely, for I still need to reset it once or twice a day, but at least it works.
Perhaps a Gloworm expert could draw a conclusion from this and recomment a proper solution???
wjb
December 2006