marvic As an overview, the engine is set at at the point of firing. The magneto is set with the points just breaking, with the brass segment of the slip ring positioned under the pick up ready to fire the cylinder on compression. The magneto gear or auto unit is then replaced, without altering the engine or magneto set positions.
Set a manual magneto to full advance, turn the armature clockwise (from the points end) until points are just breaking. Auto unit, position armature as before, but wedge the auto unit at full advance. Push onto the armature taper, attempt to hold everything still, tighten up the retaining bolt. Lots of hints on the Forum.
Dead easy, but takes practice. Stick with Beezermacc. He has done it a good few times. Quite 'andy at it, you could say.
Swarfy