Hi, Charlie, thanks for your reply.
I’m rather reluctant to take the thing apart again unless vital, the threads are bad bad bad, as I’d like the machine to do one job in the next couple of weeks before dealing with it.
Anyway.
There are no connections *at all* to the points, only a wire cut off at the exit through the grommet of the cover.
There is a thing that looks a bit like the attached (from “my old machine”) bolted to the aluminium casting that fits behing the cast iron flywheel-blower-fan. Yes, I think it has got electronic ignition. This device has a vertical pattern on it, unlike the chevrons of the attached picture, but is otherwise similar.
The black plastic encapsulated coil under the flywheel is mounted on a laminated “C” shaped metal core. There is a steel screw through the core (that does not screw into anything else) that seems to allow for dismantling the core itself. The core is bolted to the engine with two bolts. There is a magnetic rotor on the crankshaft to generate current when the engine turns.
The HT wire just pushes into the coil, a short length of copper inner being bent back up the outside of the wire to contact the inside of the hole it pushes into in the core. The HT wire goes out through a hole above the coil, and up the back of the engine to the sparking-plug.
One LT connection from the coil is earthed. The other LT connection from the coil is soldered (replacing the wire nut join) to a wire that follows alongside the HT lead out through the hole above the coil; this LT goes to one connection leg of the “thing” in the attached photo. The “thing’s” other connection goes to earth.
I’m at a loss to know how it works, but when it’s actually running, it’s fine. Then it just stops, seemingly with no spark, or possibly – hard to see – an intermittent weak spark.
There are no other cables or connections involved. No capacitor. Nothing.
