HI, Had this problem last year...supposedly there was no longer a problem when I left the dealership...and then I was nearly hit by a large truck when my horn didn't work several days later. Went back again, and a creative mechanic tried cleaning out the steering column and the inside of where this all fits. Apparently there were very fine metal filings (just wear from over the years). We've never had another problem. Hope this solves your problem too.
I hate modifying things from the stock set up but if in fact it is only the horn that is inoperative and the SRS/air bag system is OK I would put a momentary push switch on the dash. I can look at a wiring diagram and tell you what wires need to be brought to a push switch.