Through dismantleing the contents of a home, I've found a couple portable CD players. I've put in new AA batteries and both seem to be active but I can't figure out how to get the CD's to play. Of course both models need ear phones. This Koss CDP 657 series was manufactued in 1997 but the company doesn't seem to manufacture this model after all these years. I'm looking for a manual. Can anyone help me out?