I picked up some old headphones at an estate sale last week for $5. They say "Passport" on the side, with the model number HP-618. But, I can't find a darn bit of information about 'em. I've found one website on the whole of Google that mentioned the headphones being sold with a Zenith Circle-Of-Sound record player/stereo combo: http://www.worthpoint.com/worthopedia/zenith-circle-sound-phonograph-stereo-163592696 Each can has it's own volume control, which is where the problem lies: The left can only works when the volume is at about half volume. I can't find any information on the headphones, so I have no idea how to remedy the situation. Can any of you dudes point me in the right direction?