Are two colonial friends are right,
I used to work in aircraft workshops repairing and servicing aircraft parts and i was involved with Magnetos. Down in the bowels of the ship we had a little shop with a lathe, Mill etc, there was an attachment on the Lathe for winding bobbins and armatures. But i hated getting sent down to rewind Mags and High Energy Igniters, starters ect. Fiddley arsy things and being young then and always in a rush it didnt bode well when the bloody wire broke (a Lot).
I did do some bike mags back then but it was painful, a Chief Petty Officer took over and showed me how to "Do it properly" after asking why i was using HM property to fix motorcycles!
I wouldnt attempt to try it without the right tools as Trev and Trev say! Get the man who can!
Recent club runs here sugested that someone carry a spare Mag amongst the group just incase.