[Amp in sub-10 went bad?]

Tried that already. They can't look up the purchase if you pay by check...no luck

[Amp in sub-10 went bad?]

I'm looking for someone to give me some solid help. I called Klipsch and all they basically tell me is to bring my sub back to Best Buy, even though I can't find the reciept for it. Here is my problem:

Yesterday when I turned on my TV, I noticed that all my powerfull bass was gone. I have the Synergy sub-10. First thought was that it may be my reciever on a wrong setting or something like that, but that is not the case. Today I unpluged all the speakers and left just the sub connected and had the volume turned up with music input. I can hear the sub giving a faint "ratteling" sound when it recieves the signal to output the bass. This way I narrowed down that it is a problem with the sub itself, which I just purchased about 6 or 8 months ago.

I am looking for someone who can tell me exactly what the problem would be or could be and if there is anything that I can personally do to fix it because I can't bring back to Best Buy without a reciept. I assume that it is probably the amp inside the sub, but I don't have the experience to know for sure and if I can handle fixing the problem myself.

I would appreciete any input to save another $400 to go back and buy a new sub after this one only lasting the length that it did.