Thanks Grumpy for clarifying that, I did notice that the Earth wire had become slightly detached from the module ie the wire was fraying at the module. By the way, the module is not grounded on the engine casting, it is also connected by a screw which holds down the carby as well.
So the Earth wire must be grounded to get a spark, I wasn't sure whether that was essential or not. It's possible that the wire has completely come off the module because you have to squeeze everything in tight during re-assembly. If the wire has come away, can it be reconnected?
