Comcast on demand GSM-2 error

I have two TiVOs...a Raomio and a Premere...neither one can now access Comcast On Demand, both getting a GSM-2 "Service Error." Before I waste hours of time with TiVO/Comcast support, I thought I"d try here to see if anyone has a solution. Since it's both TiVOs, I suspect it's not a cable card issue, and I"m not about to "swap cards," as was suggested last time I had an On Demand problem. I don't use the feature that often, but still...
There are other threads with On Demand issues, but...

Comcast on demand GSM-2 error

Comcast on demand GSM-2 error