Horn troubleshooting

[JCHarvey]

My horn quit working after I did the 1,000 mile service. I put a couple of drops of oil on the felt pads and "jiggled" the bale on the switch at the bottom of the steering column to make sure it was securely engaged.
The horn is 6 months old so didn't think the problem was with the horn itself. I "bench tested" it by connecting the horn contacts to positive and negative and the horn works fine.
Is there a method to determining if the problem is in the switch at the bottom of the steering column or at the horn button at the steering wheel? Before I did the service work the horn had been working fine.