Found new steering column wire to replace one with sheared brass contact (I know that was a problem!) at horn ring end. Threaded it through and attached to other wires. Fuse blows and no horn. Where's the short? Step-by-step abbreviated, non descriptive trouble shooting procedure requested. Enough no horn.
In order to replace IPD horns with functioning original, which side does the round horn get positioned (drivers' side?)

Here is how the horns were in my 1964 122s when i got it. I'm not sure if they are original or not. Sorry for the image quality it was taken for different reasons.

Be sure the wires coming from the harness to the horns are not grounded, and that they are connected to the proper terminals on the horns. These wires are hot with positive 12volts and will blow the fuse if they touch ground. They only come from the fusebox to the horns. They shouldn't be too hard too trace. The switched ground, coming from the steering column should have no affect on blown fuses. If that wire was shorted to ground, your horn would stay on. If the fuse is only blowing when you press the horn button, i would suspect an improper connection at the horn.

Does the fuse blow if both horns are disconnected, being sure the wires aren't grounding?

good luck,
curtis m. white
http://thirdchoice.com

The wire in the steering columns switches ground to the horns, not voltage, so it cannot cause a short on its own. Are you sure it's hooked to the negative side of the horns? Are both horns connected with the same polarity?

The original horns need to be insulated from the body; they mount on rubber grommets. I can't remember which goes where, sorry.