not charging

You have an isolated field alternator.
(Square back)

The blue wire provides battery voltage via the ignition switch to one of the two field terminals. The other field terminal is hooked to the green wire that goes to the VR.

the VR has a switched battery voltage wire and a ground.

When the VR sees less than it's setpoint for voltage, it increases the amount of ground thus increasing the magnetic strength of the field which increases the output of the alternator.

So, what should you see on the wires...

Blue, battery voltage blue terminal to battery negative

Green, far less than battery voltage green terminal to battery plus.