Hi all! I recently picked up an AM7 system on the cheap. However the center cube is completely inop. I have checked all the wiring, swapped cubes, and reviewed all the receiver settings (Kenwood VR209). So it looks like my next point of attack will be to open up the "subwoofer box". Has anyone run into this before? Anything I should be on the lookout for other than swollen caps? Many thanks! JW