"See if the magnets in the rotor / flywheel have lost that lovin' magnetic attractive feeling. If a piece of steel does not stick, you need a replacement flywheel."
Hmmm. Not so fast.
The rotor/flywheel has NO magnets. Steel might stick to it a tiny bit if the iron bits have retained some magnetism but this is not important. Unless you want a lighter flywheel or it's physically damaged from a crash, there is no reason to replace one.
The field coil makes a magnetic field axial to the crankshaft. The rotor is aluminum alloy with iron pole pieces embedded in it. The iron bits direct the magnetic field to alternating N/S/N/S poles on the rotor circumference - these sweep past the stator coils and generate the alternator power. The regulator controls the field coil current and thus its magnetic field strength - and the alternator stator's power output.
So... if your field coil is OK, and your stator coil is OK... the rotor is just a dumb lump of metal and, barring disintegration, failure proof... most likely you have no field coil current if the stator coil is not making any voltage. Residual magnetism in the rotor can produce a volt or two with no load.
Check the regulator wiring and test voltage across the field coil. With key on and engine stopped, you should see battery voltage (or close) on the field coil's two wires. With a fully charged battery and engine running, the field coil voltage will vary as the regulator controls alternator power output trying to maintain around 14V on the battery.
