>> ^^ Do you understand how power cords are wired? If you get it wrong, Bad Things happen!
Al, I appreciate your urge not to jump to conclusion but isn't experimenting that got many further? Of course, one can just leave everything alone as GK alluded to and I do so when I believe there is no or little room for tweaking.
What's next? The hearing of one differs from day to day, from mood to mood. How do you eliminate these parameters?
We are not here to proof anything but to share our experiences.
I do however agree with the settling time, be it electrical or mechanical or magnetical.
As for cleaning as mentioned many times here on this very thread, I clean every contact regularly which is easy for access but I never claim that these actions have to do with directionality.