I had the very same problem

- horn working intermitantly though.

Checked all the wiring to the horns

- OK
Could hear the Relay clicking, took relay cover off could see the bit moving and making contact but still no sound.

Only made sound when i manually assisted the reed in the relay to make contact.

So although it looked like it should work it wasn't.

Went down the scrap yard got a relay out of a Corrola

- same type.

Hey Presto

- Working again.
