Embedded the ignition back into the bowels of the plane and to my horror... not a single pop when attempting to start. What the hell now?

Pulled the HT of the plug, inserted a new plug and the spark was completely intermittent. Rocking the prop might produce one spark out of ten passes so the signal generator was hooked to it and the plug would fire maybe 1/10th of the time. On the bench it hadn't missed a spark. No prodding or pulling on the boot end affected the intermittent spark. A good battery was plugged directly into the ignition power lead with no change. A ground wire was hooked to the plug and made to the battery ground... no change.

So, I don't know what changed between the bench testing and reinstall to the plane. The prime suspect is a cold solder connection on the center conductor coupler. If so, the ignition itself may now be damaged.
At any rate, two new ignitions were ordered a couple of weeks back and the plane will get one.