My water heater appears to have stopped heating. When I turn it on the green light comes on & then after say 20 seconds goes out. doesn't turn red just goes out. I spoke to chap where I bought it & he suggested the solenoid valve ,which I had also seen references to online ,but I have been unable to find it. I am told it should be visible but I cannot find it anywhere. Pipe does go behind fridge & I wondered if it is there? I have tried banging the pipe as suggested in case it is inside boiler casing & this appears to have done something because now when you turn on, the light goes green but on the pcb the light is flashing with like a piezo spark clicking noise but unfortunately it is still not lighting. Boiler is a Truma 10 litre type: BO model B103. Yes it is original , 1989.