For what it's worth - here's what I know and have done:
TWC broke things on either Thur or Fri March 8 or 9. Things were OK on Wednesday and were broken on Saturday.
It was obvious to me from the symptoms (more below) that they had changed something such that the virtual channel numbers for all of the in-the-clear QAM channels were being set or defaulted to virtual channel zero, which resulted in only one of them (the WXII second channel, weather) being displayed regardless of which channel one tunes to.
I called TWC Tuesday Mar 13, but true to their script, the representative refused to let me speak to a technical person - their procedures "required" her to dispatch a man in a truck to measure signal levels, and then if he deemed it appropriate he would contact a technical person.
The man in the truck came Wed, Mar 14. He agreed that signal levels were ok, played with my set for a while, and agreed to let me speak to his supervisor, who finally had Terry Cross, a technical person call me. We discussed my belief that they had started changing the PSIP's in the data streams for all the in-the-clear stations to point to virtual channel zero. He went off to investigate and called me back later to report that he had reproducted the problem with his own set after pulling the cablecard, and that they would get to the bottom of the problem as soon as possible.
A subsequent update on Friday Mar 15 indicated they were still investigating - something about something that Scientific Atlanta had done for/to them.
I tried all day today to get a further update with little luck - I tried to pass along the name Steven Medley that Dave Wolf had talked to and to suggest that if they didn't know each other, they were working on the same problem and ought to compare notes.
This is getting old - about 12 days since they broke things, and a week since I brought it to their attention.
I have a Toshiba 52HM94. Before things broke, I could tune to, for example, channel 82-4 for UNC-HD, the TV would display channel 82-4 and the program would come in. After things broke, you tune to channel 82-4, the TV displays 0, and the program from WXII -2 displays. If I rescan, the set no longer finds all the unencrypted subchannels on RF channels 82, 87, and 92. For what its worth, I asked Toshiba for and received and installed updated firmware for the 52HM94 on the slight chance and forlorn hope that it might fix the problem by handling the virtual channel 0 problem differently. It did not help.
I also have a HD tuner card for my computer. This card can still tune all the unencrypted in-the-clear channels that it could tune before IF I KEEP or RESTORE THE CHANNEL INFORMATION from scanning before things broke. But if I rescan channels with this tuner card, it finds and reports RF channel 82 as being virtual channel 0, RF channel 87 as being virtual channel 0, and RF channel 92 as being virtual channel 0 (along with some other RF channels).
Summary: the in-the-clear stations are still there, in their original places on RF channels 82 and 92 (and 87 for Discover HD). But the virtual channel identifiers are broken and this keeps some (or all???) QAM-tuner-equipped sets from being able to tune them in. Others, like my computer card, can still tune them in.
Perhaps pertinent to this problem is the information that cable companies are required by Federal Regulation 47 CFR 76.640 to properly identify subchannels for in-the-clear stations, to wit:
(iv) For each digital transport stream that includes one or more services carried in-the-clear, such transport stream shall include virtual channel data in-band in the form of . . . . .
(D) Each channel shall be identified by a one- or two-part channel number and a textual channel name. . .
It's clear that TWC is required to provide the ability for QAM tuner-equipped TV sets to tune in-the-clear retransmissions of local broadcast stations, just as they have been doing for at least the last two or three years. I can only suggest that all of us being inconvenienced by this problem to contact TWC if we have not already done so in the hopes that they will work harder and faster to fix the problem if a lot of customers are complaining than if only a couple of us are complaining.