1970s 1973 Coupe Deville Horn Issue

[34837]

Long story short, Horn (s?)were working when car purchased, suddenly not, determined not relay system, took to shop (foolishly but free); testing quickly ascertained all three units are dead.
  Utube informs me disassembling, cleaning contacts etc will solve the problem, worst part is going be grinding, drilling the rivets out.
  Has anyone cleaned these up with success?  Purchasing NOS is cost prohibitive, junkyard probably same problems.     

Although always garaged the car spent first 7 years and first 36000 in Seattle, air couldn't have helped.
   Installed a $10 Amazon Horn temporarily, now I sound like an old Toyota. Thanks, A

[Julien Abrahams]

When I had two seemingly dead horns on a '66 Eldorado. I sprayed WD40 inside the horn (literally in the opening). Then let it sit for a couple of days. Tested them, and they now both work fine.
I would also test them with a good battery, connecting it directly with jumper leads.