I had a similar problem of intermittent horn. Not to state the obvious, but the screws fastening the face of the steering wheel to the body of the steering wheel were loose. Haven't had any issues since tightening them.
I also had particulate debris indicating wear of the plunger upon the contacting ring. Out of curiosity, I did not clean or roughen anything but left it as is. No problems there, either.
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1987 FJ60 stock 2F, H55, OME heavy/heavy, ARB Front bumper, 4+ rear bumper, Wilderness system roof rack.
I'm confident enough to try it...
Dumb enough to not talk myself out of it...
And optimistic enough to hope...
...hope that I'm smart enough to get myself out of whatever I started.