I switched on the system today and no audio from Video 2. The audio is fine when muted to headphones and the other inputs produce audio as expected. I have reset the source device (DTV) and removed power from the 990 per the manual for five minutes.

Is there anything else to try before a hard reset of the 990?

The problem is gone. I turned everything in preparation to reload the firmware and voila: Audio 2 works. I guess it just needed a good night's sleep or maybe that it felt threatened.