"Delete channel" doesn't delete channel?

I have a 19" Magnavox RS 1966 color television that was unplugged for several days while we had foundation work done on the house. After plugging it back in, I used the "Auto Programing" feature on the remote control to re-learn all the channels (no cable, rabbit ear antenna only). Now I cannot delete the channels that have no signal; accessing the add/delete feature on the remote and pressing the "delete" (-) button makes the channel number turn red, but it doesn't delete the channel number. Used to be when I advanced the channels, it would only stop on those that had a signal; now, I have to go through every number to get from, say, channel 2 to channel 8 (previously they were consecutive). What's up with that?

(On a related note, pressing the "Reset" button on the remote does nothing perceptible either... although I'm not sure what it's supposed to do.)

By the way, the "delete channel" problem happens whether I access the function through the remote or via the front panel of the TV.

Any assistance is appreciated.