There is a brass ring under the steering wheel that contacts a brass
grounding contact that rubs against the ring.  After time, sections of the
ring wear and the edges of the broken parts stick out farther than the rest
of the ring.  These pieces make contact and ground the horn circuit causing
it to sound.  I pounded flat a piece of solid copper wire and soldered it to
the stump of the ring. This provided a new wear surface. No problems since.

Rico Dagastino
Munford, TN