It has been a few years since I used a VF-7401, but let me see if I can help you with the basic functionality. Working from memory here, so if someone speaks up with the actual manual or with a unit in front of them you might want to go with their information over mine.
The 7401 was a very early synthesized 2M rig from Heath, if I remember right only their 2nd or 3rd such radio. And it was pretty limited, as were all synth rigs of the day.
First, the three digits on the front display. They are the ones MHz place and the 100's and 10's kHz place. The hundreds and tens MHz and the 1's kHz are not shown. So, if you see "6.52" on the display you are tuned to 146.520 MHz, unless the "0 kHz / 5 kHz" button in the upper right is depressed, then you are tuned to 146.525 MHz.
The basic synthesizer steps in 10 kHz steps, so the radio can tune 146.520, 146.530, 146.540 etc, etc. To get the "between" freqs ending in 5 you use the "0 kHz / +5 kHz" button in the upper right corner.
The three tuning numbers in the display (the "6.52" in my example above) are changed and selected via the little push buttons under each digit. The two buttons on the lower right side "Man / Scan" and "Lock / Latch" will impact how you tune or if you can tune the radio.
The rest of it is pretty basic, the Volume and Squelch knobs should be self explanatory. The "Mode" knob will select if you are in simplex or repeater mode, and the offset of + and - 600 kHz for repeater mode should be displayed as the switch selections.
T!
