Update: Just spoke with Comcast "support", who told me:
1. they've never heard of TVGOS
2. they will not do anything to restore the TVGOS signal.
It's so nice to be a monopoly.
Leaving aside their unhelpful attitude, it's interesting to note that some of the signal probably is leaking through; just not enough to create the program listings...
After 2 weeks of no new listings, I completely reset my Panasonic DMR-EH50 (pressed the Power button for 10 seconds, then pressed both channel-up and channel-down simultaneously for 10 seconds). The channel guide was lost, the clock blinked 12:00, and the DVR went into initial setup mode.
I answered the zip code/ settop box questions, turned it off, and let it scan (and scan, and scan) for a couple of days, all to no avail, although it did find a time-signal, because it set the clock after a few hours.
Also, it found two of the PBS stations, because after scanning endlessly, it settled down on one of them for a day, and then the other, for two days.
Three days after being reset, the DVR displayed channel identifications and asked me to select which of several lineups matched my service. I selected the best one, and it immediately showed me the correct channel numbers for all the stations in my area. No program information, just the correct numbers.
It certainly seems as though some information must be getting through, or how would it have picked up the channel lineup?
There is a pony in this room: I've been wanting to switch to satellite for a couple of years, but TVGOS was a benefit that justified staying with cable. With that tether removed, it'll be easier to justify making the switch.