Replace Subwoofer

[Steve]

This one may be a little tricky. From what I can tell from your owner's manual, it looks like this system utilizes a passive subwoofer. Most of the better subwoofers out there today are active. That means they have their own amplifier and don't rely on power from the receiver. There are good passive subs out there (I thought SVS made some, but I don't see any on their site), but IMO if you're going to bother upgrading or replacing anything, it would be best to start with a new receiver, and a front set of speakers and add to the system as you go unless you're able to swing the cost of an entire setup at one time. If you don't want to do that, then my recommendation would be to contact LG and see if you can get a replacement.