I had a similar sounding problem (literally) although my tweeters Did still work. I had narrowed it down to the crossover, But instead of just sending me a new crossover as I had requested axiom decided to send me an entirely new speaker and paid to send the broken one back.

Im not sure how axiom will remidy the situation but I expect that from my past experiences you will have it fixed by the time your calibrator comes by.

Haoleb's Audio/DIY Website