When ever i turn up the volume the bass rattles in the middle sub woofer, but when i push on the grill of the subwoofer it stops. What is causing this? and How do I fix it?

 

I have the same problem. I brought it into the Acura dealer and they placed a spacer between the woofer and the metal casing it's rubbing against. It solved the problem (no rattle) for about 2 months, then it came loose. I'm bringing it in again next week for a more permanent solution.