Hook the amp up again just to see if the problem comes back. I can’t count how many times I’ve fixed aircraft problems by simply pulling a cannon plug and reseeding it.
If it does come back swap the speakers if you can just to make sure it doesn’t follow the speaker.
And also make sure it’s really the tweeter. I had an M22 that started making a rattling sound on certain notes of just one song. I thought it was coming from the tweeter until I put my finger on the dust cap of the top midrange and it went away. Turned out the dust cap had partly come unglued so Axiom shipped me a driver the next day.
Darn should have taken those typing lessons.