[Patrick L.]

OK, does it show a charge when running at a fast idle ? I should have asked that before.
With engine running, jump across the cut-out terminals for a second. Then see if the ammeter is correct. If correct, with the fan belt loose, applying power to the generator will cause it to motor slowly in the correct rotation [CW from front]. If this corrects it, fine. And it probably will. If the ammeter reads backwards in everything, charge with lights on and discharge when running, then the wires on the ammeter need to be switched.