Rep Power: 748

Sounds like you have a burnt voice coil. Get a voltmeter and test the impedance of the coil that is bad and if it doesn't read the proper impedance then one of the coils are burnt and it will need a recone. That being said take it back to the store you bought it from and see if they will honor the warranty. Some places still do it but I know some don't cover burnt voice coils because they consider that abuse. When you get your new subwoofer or get it replaced make sure that you break it in properly. Play it at a moderate level for a couple of weeks so that the subwoofer has a chance to break in.