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If you read all of the posts Zenith made he mentions that sometimes the PLL (Phase Locked Loop) oscillator will not lock on the frequencies at the extreme limits and toggling the switch could jog it into operating. So the switch might jog other things unfortunately.
Even though the RF-IF switch is set to 30-50MHz (IF frequencies), the change in the EPROM program really uses the RF oscillator section, not the IF oscillator when you select a frequency outside the normal range.
As designed the RF oscillator selection powers up the RF output amplifier not the IF output amplifier. The IF amplifier puts out a signal that is 100 times larger than the RF amplifier. (The TV tuner has a gain of about 100.) So the RF amplifier output is too small for use injecting into the TV IF. On the other hand the IF amplifier output is so large it would overload the TV RF (antenna) input. The switch mod allows you to select whichever output amplifier (level range) you want.
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