I am assuming that these units are known suspect. Otherwise its bang one on and see what it does after checking for direct shorts.
The principle is simple enough. Spin the coils in a magnetic field and there should be an electric charge made. So it is possible to create a base that will fit a drill and spin the coils, or unit, up and measure an output. A big magnet out of something else might be used to prove something is happening. Clearly if there is no action and the unit is stripped to only wire, not including ancillaries, points etc, then it suggests an internal failure loosing the charge. 'Tiz bug red. The ancillaries and points can be static tested. So in a way the values are a nicety, as if it has the fizz on whizz it should do the bizz. In reality there might be a leak of charge enough to make the unit unreliable. That is more difficult to check and would require some degree of accuracy. Not sure if that helps or I am telling you what you already know. I claim no huge successes with mags. I have won, and have lost.
