Ok, this is what I did. I went to www.Rabbitears.info
(can also use TVFool, FCC, or antennaweb.org etc)
“IF” the digital number is not already in use for another RF, then this is what should happen on your TiVo (and many TV brands do the same thing, like my Panasonic about 6 years old).
If you punch in the following RF numbers you should get its corresponding digital number (take into account the “IF” statement above).
RF = Digital Number
7 = 7.1
9 = 9.1
28 = 62.1
27 = 26.1
48 = 4.1
36 = 5.1
And so on and so on etc.
If you punch in 4 or 5 or 26 as an RF then there will be snow when looking for an analog, then a black screen when looking for a digital. If neither type of channel(s) are associated with that RF the TiVo will get nothing. Now in this case this is where my Panasonic TV would differ. If I punched in 4 on it, and lived in your area it would look up the RF of 48 and give me channel 4.1.
So on the TiVo in order to get 4.1 there will be two ways to get 4.1 directly.
Punch in 4.1
Punch in 48
If you punch in just 4 it will look first for analog 4 then any digital associated to RF 4, there is none so it gives you nothing; so then you have to hit “up channel” to get it OR enter the 4.1 or 48
Hopefully, you are now making progress on tuning into channels and working on a plan to help stop the channels from breaking up. In order to make the fastest progress you will want to “fine tune” the antenna system as best as you can to get the RS corrected and uncorrected as close to “0” as you can. Every time you see the “RS uncorrected” above “0” you will see break up. That fine tuning will include everything from antenna aiming to the cables (particularly at the back of the TiVo).
As others have said the TiVo tuner is not the best in the world; it could be a good deal better.