CB750F Flat-Rate Motorcycle Inspection and Charging Issues

The weather’s been iffy, so…
Progress has been really slow.
 

 
We adjusted the headlight aim
 

 
We went out in the humid heat and got it done! All finished!
 

 
Brings back memories—something about the CB750F
 

 
A system I’ve never seen before? I don’t have the manual, so I’m a bit worried
According to the wiring diagram, it looks like current probably goes to the rotor through the brushes, creating an electromagnet-type structure
The stator shows no signs of burning
The resistance values look fine too, so it’s probably the rotor?
Holding off for now