All these type machines are magnetised after assembly.
I presume this is done with a high-current pulse through one of the coils, right?
Seems to me you might be able to remagnitize one by the following procedure:
- Hook a bunch of batteries in series to come up with a "hard" high-voltage DC source.
- Hook this to one coil of the Amtek through a big resistor to provide a trickle current. The armature will turn to a position where the energized coil is lined up with the still moderately-magnetized permanent magnets, with the current in the energized coil producing a field in the correct direction to remagnitize the magnets (though far to small to do so).
- Short the resistor with a fuse, or a piece of wire significantly thinner than the wire in the coil. A burst of very high current will flow and then the fuse will blow. (Beware of bouncing drops of molten metal, which could start a fire. So do this somewhere in a shop with no flammable material nearby.) The burst of current will remagnize the magnets while the fuse SHOULD blow before it fries the coil.
Chancy and may fry the motor. But if it's already trashed by loss of magnetization why not give it a shot?
(Note that I didn't suggest a charged capacitor because it may "ring", reverse charging the cap (which could damage an electrolytic) and/or produce an oscillating field with decay, which could DEmagnetize the magnets even further.