Ok. the way i was reading it was, it had been done.
Doubtful the HEP704 is causing the static in one channel. More likely caps or resistors in the tone amp, equalizer, or the driver section of the amp or even dirty contacts in the switches and pots. Is the static in ALL Functions (aux/Phono/FM/AM/tape monitor)? Have you cleaned the controls yet with de-Oxit? If not, clean them good. You may have to pull the boards out individually with the pots on to get them clean enough. Especially the rotary switches. Try pulling the jumpers from the back and see if you still get the static. Clean them and the jacks while they are out. If you still get static then it's in the amplifier. If not then it's before the jumpers. Which side is the static and noise. The HEP704 is on the RIGHT SIDE. Clean it before making the order. That way if it does clear up..................
If you have another amp, you can make a probe with a rca cable, and a .01cap attached to the center lead. Cut the plug off one end and separate te center and outer leads by about 2'. Insulate the outer lead and out an alligator clip on it. Attach this to chassis ground. Solder a .01 cap to the center ground (a orange drop will work). Heatshrink all but the tip of the probe end. Then probe each component, and switch contact, working back from the drivers (both sides of each component) to find where the static is coming from.
Seriously, clean everything before ordering the parts. You may find you don't need them all, except whats necessary to clean up the cheesy work. I'd leave the HEP704 and the GE7462 intact unless they prove to be the problem. of the two The GE is more likely than the HEP704. But of all the FISHER Transistor units I've had come thru I've only replaced one transistor in one unit. and that was on a tone board.
Larry