The internal loop supply on my 32 is 18 volts.

That is possible because it uses a transistor driver for the selector magnet.

That is why the 32 is polarity sensitive.

I believe the selector magnet is actually driven with 1/2 amp at -20 volts. So it would be relatively few turns and low inductance.

I suspect all the same is true for a 33.

Tom   N3CRK