At least reverse polarity doesn't destroy it, as it does with so many things.

New part arriving tomorrow or Wednesday, so should be running Wednesday night.

By the way, what thread are the screws on these? They don't seem to be BA, or is my eyesight getting bad?

The next job I think will be to move the LPG mixer plate right up to the mouth of the intake plenum and start removing all the petrol stuff and extraneous hoses, switches and sensors from under the bonnet. Too much clutter and poor access.