Thanks Gadge, that has validated the interpretation we had of the Magister (that it is simply a crude capacitive discharge ignition system, with a very small charge capacity and therefore a very small capacitor). More importantly, it has confirmed that it uses a typical charge voltage (about 300 Volts) and has given component values and coil-winding data. There seems no obstacle now to anyone with sufficient enthusiasm, repairing or restoring Magister systems.
I'm a bit doubtful about the wisdom of having used aluminium wire on the first version of the feed coil, partly because it is about three times the bulk of copper for the same conductivity level, and partly because unless it is high purity, it is difficult to protect from corrosion over the long term. However from the restorer's point of view, if the feed coil armature has room for aluminium (as, it seems, it must), there should be scads of room to rewind it in copper.
Personally I'd still like to know more about the physical layout of the encapsulated parts in that bakelite "earphone" housing. It will also be interesting to see whether people find convenient ways to remove the epoxy or whateve that potting material is, without damaging the earphone housing.
