I bought some "factory outlet" Axiom M40 towers, and they sounded great as soon as I plugged them in. The only cosmetic flaws were some "streaks" on one of the tower's tweeter domes, like some dirty water dried there. Now I know this probably wouldn't affect the sound, but I have a bad habit of taking things apart for the smallest reasons, so I took the tweeter out of the tower and unscrewed the other four screws, assuming it would simply remove the plastic frame off the front of the tweeter. I was wrong -- the aluminum dome is attached to the front plastic frame, and what I did by removing the second set of four screws was to remove the dome from the magnet. I immediately put it back together (there are "key posts" for alignment and the bottom of the tweeter dome fits in a circular gap between the two concentric magnets) and played some trumpet concertos. Immediately I noticed a very small buzzing coming from the tweeter I took apart when the trumpet played high and loud! I took the tweeter apart again, thinking the aligment was off (how could it be?) and looked at the gap where the bottom of the dome slips in. There is a dark, thin grease-like substance filling *most* of the gap where the dome fits in (between the two concentric magnets). I assumed the problem was that 1/5 of the circular gap no longer had any of this grease, so I took a very small amount of bicycle spoke grease and filled the gap, and re-assembled the tweeter. On the same music, the buzz is gone! But did I ruin the tweeter in the long-term? What kind of "grease" really belongs there? Thanks for any advice!