Just wanted to say that I have been told the same many times. It is so easy to use muscle but even easier when you learn how to not use muscle. The exercise Mark Murray described is one of a few that he has taught at our dojo and has become increasingly useful in developing that aspect of training. I can't do it consistently yet but I have these little moments sometimes that give me a glimpse of where I am heading and it's pretty cool.
Being recently off of a very long and frustrating plateau myself I feel your pain. You only have two real choices. Keep on going or quit. I don't know about you, but I'm not a quitter. I just try to keep in mind the words from the book Mastery that the time spent on a plateau seemingly going nowhere is actually the time when you are learning the most.