4 years ago I added a 12 volt aftermarket horn relay to the 50.

I few days ago the horn quit working so I replaced the relay.

it tested fine and worked.

well the horn went out again today.
quick power test to the terminal on the horn shows it works.

inspected the wires I could see and they look fine.

of course I cannot look at the mast wire.

What would cause 2 horn relays to go?
thanks