Close and the fix is related to what you wrote, clem53. Verizon support said that they sent out an update and the update reset some settings. That would explain why the sound was working before on the media server and suddenly stopped one day. If this happens to you, try this sequence, menu on the remote, settings, audio&video, audio, set-top box volume. Use the up and down arrow keys to set the volume and press OK.
Things that aren't explained, not that I really care. Why did this setting only affect the media server and not the media client boxes? Why was the setting on the replacement media server also reset? If, when the new media server was powered on, some system at Verizon sensed that it needed the updated too, why isn't the issue I reported affecting a lot of subscribers?