That's me, Rob. The left sub is the one that got damaged, but it works 95% of the time. Only during high volume sustained bass at 30Hz do I get a slight 60Hz buz (I have a hokie bass CD that has that tone in one of the tracks).
Under normal conditions, it doesn't rear its ugly head but it drives me crazy knowing it's there. And I still hate the idea of messing with it replacing the subs with a different brand after I got the sound exactly right...
Last night, my wife and I listened to hours of CDs and we never heard the buz. Perhaps the best repair is to throw away the bass CD?