After much frustration, including no progress with Comcast and no replies to emails to TiVo, I decided to look on the TiVo forums to see if anyone else was having issues with cablecards. Lo and behold, I’m not the only who was having trouble.

One user suggested to repeat the guided setup.¹ In the cablecard installation instructions, TiVo recommends a guided setup before the cable guy gets there.

So I repeated the guided setup and, what do you know, both tuners are now working. This closes the Comcast Saga.

1. A long drawn out process that sets up your TiVo when you initially install it or change service providers. [↩]