easy obtainable -- do be aware that the case seal is a critical componant-- do check this seal - make sure all three fixiing screws pull the outer case to the chassis.
also check the pilot flame is playing onto the tip of the thermocouple if it requires replacing.
its a bitch to tighten as it is at the back of the boiler which will lie close to the wall..
dave ex thorn eng.
dave broadbent, June 2007
