I have an issue with the horn on my 78. It doesn't work. Any recommendations on where to start and how do I get the horn button off?

IIRC, mine just pulls off.  It's held on by several spring fingers.  Just try to grip it evenly all around and pull.  "78 might have been different but I doubt it.

Two possibilities for it not working. Most likely is the horn(s) themselves.  There's an adjustment screw on the back which changes the gap inside.  With 12 V applied to the horn, try running the screw in and out to see if you can get any noise out of it.  The horn is basically a vibrating diaphragm and the gap is for tuning it.  If the horn doesn't work and the horn button is applying 12 V to the horn and it still doesn't work, then it's the horn.

If that doesn't work, the next place to check is the horn relay.  Not sure where it is.  While someone is pressing the horn button, check for voltage at both the horn and the input and output of the relay.

Lastly is the contacts in the steering wheel itself.  Check those for oxidation and polish w/ emery cloth if they look crudy.

The horn relay should be hanging under the dash to the left of the steering column.  It has fingers that hold it in place, so you need both hands up there to release it.

Thanks, Bill, I didn't get a chance to look at it today. I should be able to look at it tomorrow. I will keep you posted.

Well I had time to look at my horn issue today. The horn button did pop right off by applying pressure with my hands on both sides. I took the contact ring out and didn't see any issues with it. I tested the horn contact with my test light and am not getting any juice. I ran a jumper to both horns and they both work so I started looking under the dash for the relay. I couldn't find it initially, so I pulled out a wiring diagram. I found what I believe is the plug for the relay ( it has a green, orange and black wire as stated on the wiring diagram); but there is some kind of fabricated plug in the plug for the relay. The wire from this plug goes to some type of relay looking type thingy ( I have no idea what this is). I could try to unplug it and see what doesn't work; but I am reluctant to do so. I'm afraid to test my luck. The car starts and runs fine. Electrical stuff is not my strong suit so I may need to get some help from someone else.