As far as I can tell ( without disconnecting the cable ) the fat wire is connected to the input without the shield. It is now under the shrink wrap, a stray shield wire maybe touching the input connection? I did cut it back as per instructions. The other end of shield is soldered to earth. The middle cable is on number two (2) of V1.
I have noticed that one of the green wires from the PT to pilot light, it may have been touching both connections? Also the same green wire going to the middle valve ( V2), there is a right/wrong way to connect them to poles 2 and 7..