A tuning adapter always comes from the cable company, just like a CableCard. But not all cable companies use them, and some use them in some locations and not others.

Are you missing any channels?

I am missing around 100 channels. The Optimum technician told me I need a tuner. Optimum told me I could get one at the Optimum store. At the store they said that they never had them and never will.
I had a 3 way call with Tivo and Optimum, Optimum told us that I could get one on Amazon.... they do not supply the tuner adapters. The Tivo guy was like all other cable providers are providing them. Optimum stated that they will not supply them and hung up on the conversation.

That's bizarre. Unfortunately, I think you need to just persevere and call them back.

My tuning adapter was supplied by the cable company(Cox Communications) that I subscribe too. I have used the adapter successfully for a number of years with a Tivo Bolt Plus. All of this came to a crashing halt until I sustained a disk drive failure with the Bolt Plus. I sent the unit to Weaknees and I got the External Drive. The turnaround time for the repair took about a week. I initiated another Guided Setup with no problems. I noticed that I wasn't getting all of the channels like I was before. Long Story Short, I acquired another Tuner adapter and a cable card from Cox Communications. The install was easy. I have a fair number of channels, but the only channels that work are 1 - 11. Everything else, I receive the dreaded "no authorization message which is odd considering I was getting all channels prior to the hard drive crash. I talked to technical support at Cox Communications and we verified all of the information on the cable card. All of the recordings that I had were wiped out when the unit was repaired. I did manage to create a PASS for one program and the Tivo records the program without any problems. My dilemma now is to get the rest of those channels. I have even gone so far to test each channel and the signal strength is 100%. Is there anyone else out there that is experiencing the same issue after having their unit repaired? Weaknees did a good job on repairing my unit. I'm just trying to understanding the reason why I can't get all of my channels now? I am going to continue to grind on this problem. If I find a solution, I will then post it.