Low voltage at gauge, no charge?

VERY good. Breaker, yes. In stock form the HL power is fed off the black ammeter wire, ONLY fuse in the fuse link. The HL switch has a breaker in/ on the switch. (I don't know about the early girls they may be external) Normall inside the switch.
How well I know about the breaker. When I upgraded the headlights on Gladys, my 75 Ford truck to H4 Halogens, I didn't put the upgraded relay harness in. Coming home from work after closing, the headlights flashed morse code until I dimmed them. I got the upgraded harness with relays and it's never done it again and the headlight switch is cool as a cucumber. lol