ADDS Regent 25

Hi all, I recently acquired the above mentioned terminal in great shape. On power on, it shows a white screen with black characters, all keys work and echo locally. But when connected to a known good serial cable with a 9600 getty, I get maybe a little gibberish and no more local echo on keystrokes. Tweaking the baud rate dips has no effect, and possibly of note, the dip for toggling between white on black and black on white has no effect either. So, looking inside I don't see anything obviously wrong, no blown caps or damaged traces, but there are some unlabeled dip switches on the main board. Before I go further diagnosing, does anyone know what these switches do, or what their default configuration should be? Is anyone else operating one of these that could share experiences. Thanks, --sma