how can I add channels to my panasonic vcr?

The coax input on our tv got fried in a thunderstorm, so we bought a used vcr to use as a tuner. We don't have a users manual for it, so we've had to try to figure out the set up on our own. At first we were able to go to channels 2 through 99, but didn't get a clear signal on any of the channels. Using the "what the heck, I'll try this button" method, I managed to get a clear signal on all the channels up to 42. Now we have a new problem: we don't get channels 42 through 97. If you try to go past 42 using the channel up button, it jumps right to 98. If you try to use the number pad from the remote, it won't accept any first digit between 5 and 8, or second digits that don't lead to channels 2-42 or 98-99. It's as if you hadn't pushed the button at all. Anyone have any clue how to add channels? It's a Panasonic model PV-2720.

Thanks in advance for any suggestions!

Kerry