I recently bought 2 M60's and a VP150 from the factory outlet. I noticed during a movie a crackling from one of the tweeters on the M60. Later on, I noticed during pink noise that one speaker just sounded tonally different than the others, and had to be 3db hotter to achieve the same level on my SPL meter. I discovered that the mid-driver wasn't working on the other M60. I opened up the back where the binding posts are, and it ended up being bad connections to the crossover board on both speakers.
I would recommend cracking open the back of the speaker and wiggling the wiring where it connects to the board a little bit. If you can get the tweeter to come back in, let Axiom know. They ended up sending me two whole new speakers. If it's a crossover, and not a tweeter, you will probably get a replacement speaker, and a return label to send the bad one back.
