Georgina,
well, if there are charges and rotations involved for the properties of the electron, then classically one could expect a magnetic dipole moment for that particle to be present. But you withdrew that classical picture. Somehow you nonetheless want to establish a connection between the classical assumptions of electromagnetism for a moving gyroscope (rotating around center of mass, conductor, moving charges, currents, magnetic fields of that current, Lenz Law) with the classical picture of an electron (rotating around center of mass, electron-ness, conductor inside, moving charges, currents, magnetic fields of that current, Lenz law). I really do not buy into this kind of analogy. For me it is an analogy, but one that is not fully symmetric when it comes to the governing laws that are responsible for the behaviour of these two distinct objects (see below).
For me it is clear that a Stern-Gerlach experiment with little gyroscopes will not result in the well-known open-mouth figure. There will not new laws of electromagnetism be discovered in such an experiment. The only thing that one possibly could discover is that one had incorrectly applied the known laws of electromagnetism and the result must be explained by properly applying these laws.
But I really do not believe that the same will also be true for the electron's quantized spin, or in other words, I don't think that the concept of a quantized spin is due to incorrectly applied laws of electromagnetism.
Why? If one could take the gyroscope experiments as an alternative replacement of a real Stern-Gerlach experiment, and thus could switch between the micro- and the macro level when making inferences or predictions, then an electron in an inhomogeneous magnetic field should not experience a classical Lorenz force. But the truth is that in the case of a gyroscope in an inhomogeneous magnetic field, Lenz Law must be applied, whereas in the case of an electron in an inhomogeneous magnetic field, the Lorentz force is dominant (there are indeed experiments thinkable where one can measure up- and down spins of electrons in an inhomogeneous magnetic field, but these effects are all purely quantum-mechanical and one needs a different experimental setup than that of an SG-experiment).
For all these reasons I also do not believe that if one replaces electrons in an SG-experiment with silver atoms then a combination of Faraday's law of induction and the Lorentz force should apply (what would be no other than Lenz law giving the directions of forces). This cannot be the case since otherwise the open-mouth figure would look different, means spin was not quantized but the figure would show continuous impacts along the z-axis of the figure.
That's simply the facts: Faraday's law as well as the Lorentz force do not operate according to "all-or-nothing" in relation to the angle an object encounters these forces, but according to trigonometric functions.
For giving you some additional food for thought about the analogies of single particles with aggregates of particles, I post you a section from a wiki article:
"In real materials the Lorentz force is inadequate to describe the collective behaviour of charged particles, both in principle and as a matter of computation. The charged particles in a material medium not only respond to the E and B fields but also generate these fields. Complex transport equations must be solved to determine the time and spatial response of charges, for example, the Boltzmann equation or the Fokker-Planck equation or the Navier-Stokes equations. For example, see magnetohydrodynamics, fluid dynamics, electrohydrodynamics, superconductivity, stellar evolution. An entire physical apparatus for dealing with these matters has developed. See for example, Green-Kubo relations and Green's function (many-body theory)."