Ignition puzzle

[Tony Griffiths]

Tony,

may I ask if you have come to a conclusion about what caused the lack of spark, or is it that the extra earth lead (now removed?) got enough spark through for it all to start working again and is now no longer needed?

Once an earth had been established (directly to the battery) and a spark achieved, with the earth to the battery removed it continued to work and has continued to do so. To be sure it will, I'm going to earth the fixed contact point - and the distributor body - to the dynamo housing.