Help Guys Please/ Not Charging

[Woody]

i PULLED MY BABY OUT TODAY FOR A FIRST RIDE. 3 YEARS IN THE MAKING. THE CHARGING CIRCUIT IS NOT WORKING. THE IDIOT LIGHT IS ON. WITH THE 14 TERMINAL PLUG AT THE BACK DISCONNECTED AND IGNITION ON I HAVE POWER AT THE REG. pLUG IT BACK IN NO POWER AT THE REG?????????????
IF I RUN THE CAR AND JUMPER POWER TO THE FIELD SIDE OF THE REG IT CHARGES. WHY DO I LOSE POWER WHEN I PLUG THAT CONNECTOR BACK IN. I HAVE PULLED MY HAIR OUT TRYING TO FOLLOW THE SCHEMATICS.
P.S. IT IS A 70 911E
ANY SUGGESTIONS WOULD BE APPRECIATED
THANKS WOODY