(quoted from post at 22:44:41 07/25/16) I have linked my Charging Troubleshooting Procedure. It covers BOTH Cutout Relay as well as Voltage Regulator charging systems as no need to reinvent the wheel for each of the thousand times this question is asked.
In Par 5 it tells how to by pass the VR or relay by grounding the Gennys FLD post to see if non charging is a genny versus a VR problem.
With a simple jumper wire you can diagnose many charging problems without the need for expensive equipment
Make sure the Genny and VR and/or Cutout Relay and especially the light switch Low/High control switch/box IS WELL GROUNDED since if not she wont charge properly
Make sure the Genny is Polarized (see my procedure)
Print it out and take to the shop and it should help you find the problem
http://www.ytmag.com/cgi-bin/viewit.cgi?bd=jd&th=458743
John T
John Ts Charging Troubleshooting