if just the headlights are affected, and not tail or instrument lights, as Martin said, check the dimmer switch. Next I would check the headlight switch although, instead of a circuit breaker, there was a short fuse in the switch
(as seen here https://www.americanclassic.com/1955-59-Headlamp-Switch/productinfo/53%2D112/ ).
I am not sure if the fuse affects all lights or just headlights. Normally, a fuse would just quit working, but I would check it out anyway.
