Mark, the coils, though rare, are not nearly as rare as working Magister modules. I suspect Grant will be able to put his hands on a coil to find out its characteristics experimentally - but they are too rare to risk damaging by putting one into an experimental ignition circuit. By connecting the coil only to a diode and a fairly small high voltage capacitor, we can learn what its output voltage is. Later, Grant might be able to physically measure a coil. When we know the dimensions of the wire winding (outside dimensions less core size) and the wire diameter, we can estimate the number of turns so that new coils could be wound. Then a new coil with the same characteristics as an original one, could be used in the actual ignition circuit. This minimises the risk of damaging rare items.
Of course once a working ignition system has been produced and tested, so we know it isn't a coil-killer, it might be feasible to run it from an original coil instead of a reproduction one. The aim here is to duplicate the Magister as far as possible rather than parallel-engineer an equivalent item. Unfortunately there isn't all that much chance of making a physically-accurate reproduction of the module itself, because it is assembled in a specially-designed chunk of Bakelite and encapsulated in epoxy. I suspect we can fairly easily produce a device that performs like a Magister but is actually built in a small tin box rather than a Bakelite housing that looks like a WW2 earphone. Once that is accomplished and the design information posted, somebody may or may not start turning up pieces of Bakelite and trying to make a real one - or a whole batch of real ones, to get a lot of Magister-equipped engines back into operation.
