All the info I have says Orange spark is weak but would it be able to jump a gap almost 15mm? Unless it loses it's strength in cylinder pressure...

I'll get in the shed with the Multimeter later when it cools down a bit, but which resister do you mean, rg? It already had EI when I bought the car and the ballast resistor had been removed.

Thanks for the input fellas.

I have a spare ignition barrel on the other B110 but it is the steering lock type so a pain to remove. The ignition switch seems the next likely place to check, though I'd like to be sure before I pull the other one out....