Tivo not receiving local channels

Hello,

My Tivo recently stopped receiving only local channels.  I have gone through all of the troubleshooting steps, including spending hours on Comcast's Chat helpline.  Any higher channels, like TNT or Comedy Central, are ok.  I have been trying to search past posts and think maybe there is an account configuration error?  

The actual error is V52.  I have checked signal strength and for these channels it's zero.  For other channels, it's in the 70s-80s.  This worked fine until about 10 days ago.  I'm hoping maybe  @ComcastTeds will see this - I saw on the Tivo forums that he is knowledgeable about Tivos and CableCards.  Or that maybe someone could tell me how to contact higher level tech support.

Thanks for your help,

Christy