When my Polk audio is off I started hearing a clicking sound from the subwoofer. I find that it does not work but its power is on. We mainly use our system with the TV and do not use it often, never loud use. Our system is 3 years old. If you unplug and replug the r/lfe in line, you get a brief lound burst of loud sound so it appears that the subwoofer is capable but otherwise no sound. Any ideas?