Bumping this now ancient thread, again!
Got my truck back on the road for the first time in years yesterday and you can imagine my (and the adjacent drivers) surprise when my left resulted in a HOOOONK. I used hand signals for the rest of the test drive
I havent gotten my wheel off yet, but I suspect its the signal lever being loose on the switch body. It had been wobbly for years when I was driving it. Perhaps I'll just go ahead and replace the whole thing to save me a headache later.