I just purchased a NH600D on ebay for $22.00 (including shipping. But there was a problem with it that I thought that I might be OK with. In the description he said that it played the discs fine but the volume control cannat be decreased from full on. Well, I received it yesterday and the volume does work on the unit. Perhaps he thought that the volume was the 2 buttons at the bottom because when you press the navi/-menu button the volume increases- pressing the group button also icreases the volume. Sounds to me that this is a software mapping problem. Is this the case? Do I go into the service mode to fix this?