its not rocket science more brain damage sometimes , a local builder to me had an issue with a boiler with 3 of them standing around this brand new boiler ,i had a quick look and sussed it was a pcb problem and told the guy to get a new board and i would fit it in the morning , this builder was a bit slippery and he went and bought another boiler and installed it which for some strange had the same fault, I gave him a call and asked him if he wanted me to have a look, I moved a plug on the pcb and the boiler worked perfectly,i phoned the guy and he was in the process of buying his third boiler lol