My issue is with the SDS100. Unit turns on. Set Scan Selection shows. When I turn knob screen drops down to Settings. When knob is turned again screen jumps back up to Set Scan position. I cannot scroll to any other screen. The same issue is also with the volume, it is at vol level of 6, when knob is turned it only goes to level 7. When I turn knob again it returns to vol level 6. Any advise?