Horn issue...

My horn worked fine. Then I swapped engines. Then the horn didn't work. I can hear the relay clicking, but no horn. I checked the ground by putting power directly to the horn wire, horn works, that's good. Installed a new relay, horn works. Two days later, same issue. I can hear the relay clicking, but no horn. Can I be killing the relay somehow? Anyone ever had this issue? Outcome?

Brian