Aiwa AV-DV75 "rustling sound speakers" Questions

speakers do not My AV-DV75 unit seems to be working fine. The center speaker has sound but the others do not. I have lost my owners manual and may be missing something as simple as an extra connection

...sound is okay, but when anything loud happens like a crash or boom, it literally sounds like one of the speakers has blown. And it's not just loud things, but even high end sounds like rustling wind. ...