Did the unplugged reset to no avail.
Thought I'd covered everything possible from my side, so I called tech support and described the situation -- check switch, front panel reset, unplugged reset, other channels from the same transponder showing fine, etc. The lady at tech support was very patient and seemed knowledgeable. She was also perplexed and asked if i'd hold while she checked a few things. When she came back she asked, "Is it possible you locked those channels out?"…
d'Oh! Id checked the channel lists, but not the channel locks. I have no idea why I locked them out, but I sure as **** did. I apologized to the tech and do the same for all of you. Sometimes, even if you are attempting to be resourceful and thorough, you end up being a doofus! Thanks again for your help. Now I'm all set for the next HD loaded tech chat!