I can't really say if 748 coils are the best choice for your bike but they sure play no role on power valve issues.
The reasons for having problems with the Rc Valves are a) the PGM unit obviously; b) problems with the servo and/ or c) a malfunctioning rectifier.
a) PGM unit :
If I remember correct, when I received your unit, I told you that everything looked fine and I wasn't able to find any problems. Though, I still changed all the electronic parts of the Rc Valve circuit... just to be on the safe side.
Please, correct me if I'm wrong as it's been a month back and I've repaired quite a few Pgm units since then.
b) Servo unit ...but as you said it works fine.
I take it that it moves freely when supplied with +12V and you have measured the values of the potentiometer and the wiper with the outer lugs give a total resistance of about 5K Ohm.
c) Reg/ rec.
You already ordered a new one, so no real problems here.
The "function" switch shorts two wires when pushed.
The color of the wires are Blue - Green & Red, you should be able to find them easily on the orange fitment that comes out of the PgmIV unit and connects to the corresponding fitment of the LCD.
Please, check that the "function" switch works properly.
Do you have a "warn" light on the panel? Is it "on" or "off"?
Actually, a photo from your dashboard would be really helpful...
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