Robbie, the fault lies with the instructor doing the check ride for using the wrong terminology. If the RPM is down in a 500 then it is throttle not power, doesnt really matter how you look at it. As for throttle friction that is down to you, you have it set where you like it. If you have it undone the tendency is to close the throttle as you pull the lever up. The term power in any helicopter is always collective, go back to basic effects of controls the first flight lesson ( well it is in Europe ) collective controls power and height, throttle controls engine and rotor rpm.