I've got one of the above boilers, and everyime it fires up there's a VERY loud thumping buzz. This noise goes on for 2 or 3 minutes. It seems it's the pcb controlling (or not) the solenoid which is screwed (technical term meaning broke!). Can anyone help with the part no. for this? It seems that even with the part number I might be struggling to get hold of a spare, so does anyone know if there's a "swap out" alternative?