Joe... i think you need to place this thread in the pre 84 forum.
I recommend that you firstly start with taking the horn off, or testing it on the car like advised... that way you can figure out if the horn is okay or not... then work backwoods.
The horn may only need some adjusting, i recall on an old car i had in my younger days that they needed oiling...im not sure now..
Then if you know the horn is okay, then work on the wiring system.
I have the wiring diagram for my 69 Vette, i can copy it at work and give you a copy... it should be the same..
OK...;27