Here's what today has revealed so far:
The plug had some chunky carbon deposits on it, so I cleaned and regapped it. The ignition would fire the plug when I turned on the ignition. When I spun the prop so the magnet passed the sensor, no spark. I pulled the sensor and located a wire (the blue one that is soldered onto the sensor mount - so I'm guessing it's the ground) that had broken. I resoldered the wire, reassembled, and still no spark when the magnet passes the sensor. The battery is a new battery, fully charged. Bypassing the swtich yields the same results. I've inspected all the wires to the sensor and after the ground was fixed, the others look okay. I'll try starting it later today.
Thanks
sam