Set Rotor Angle

Hello, I'm sort of new to the whole in game coding thing, but I am no stranger to C#. I have been playing around with various way to try and do this based on examples I have see, it is basically a "Rotate Solar Panels until certain power level achieved" script. Mostly playing with it.

Right now I am trying to adjust the angle of the rotor back 5 degrees if the power percentage is below a certain threshold, but I am having trouble actually adjusting the angle.

I have tried this using the...

Set Rotor Angle