I had the same intermittent horn problem....I`ve checked everything from the horn itself behind the bumper, its earth, the cable etc, with no improvement ....so I wanted to check the horn push in the steering wheel and the cables to it, inside the steering cowl. All I discovered was how to remove and refit the cowl.
But after searching on line i found that the horn push/airbag is held in by a clip mechanism....on the front of the steering wheel is 2 small holes left and right side. Where I was expecting to see a torx screw I saw 2 parallel metal strips. To remove the horn I`m told to insert a small flat screw driver between the parallel metal on each side and twist to release the horn. I never got as far as removing the horn push, as after fiddling with a screwdriver in the holes, the horn worked 100% and even sounded clearer...not the usual pathetic squeak. I`ve probably improved the earth continuity