Has anyone experienced the display going blank on a Kenwood TH-F6? I got this unit from a friend who was liquidating their ex's left over radios. It worked fine up until a couple of days ago. It still works fine except for the blank display. It didn't get dropped so I'm ruling out a loose connection for now. Plus no matter which way I whack on it nothing changes. Without a display it's kind of a small boat anchor.