I check the screws on the active subwoofer and where tight, the only screw on the back of the sub that where not tight where the screws around the switches, knob and plug section, so tighten all those up. The passive subwoofer, I took the screws out to see if I can remove it. but it seal on there tight. So i put the screws back in, but one screw wouldn't screw back in kept feeling like it was starting to cross thread so I pulled it back out push the screw back in and the thread insert fell inside the subwoofer, don't know why guess it was loose and that why it wouldn't thread back in the right way. Wish I would have just tighten them and left it alone now I have one hole with no screw. Not sure how to get that passive subwoofer out to fix it. Just my luck, I have bad luck.