625 "auto tune" timers..am I missing something?

[catnap1972]

On my old 625 (before it died), I could set the timer to auto tune a certain channel when the TV turns on in the morning (use it for an alarm clock), but it doesn't seem to work on the replacement (auto tune timer only functions for 1 minute, then goes back to whatever channel it was on beforehand). Doesn't seem to be any way for me to change the duration (greyed out), so am I either missing something or is the feature broken in some alliterations of the 625?