For me this is really going to be incredibly hard. I can't tell you how many times this weekend I thought I started to make progress (mind you very minor progress) and would then catch myself using my shoulders.
Well, as someone who has gone through it all himself, let me say that your observations are crucial to correcting yourself. It's when someone uses a lot of shoulder, yet they convince themselves that they "were almost doing that jin/kokyu stuff already" that they're doomed to failure. I could feel the guys who were already doing some of it or almost already doing it... and they're not the ones who thought they were already doing some of it!
And really, I say this caution not to chastise anyone or put them in their place... I say it because I know from experience that the new guys who think they are "already doing this to some real degree" are doomed. But I don't say a lot to try and change their minds when I hear them say those potentially suicidal words because it seldom changes their minds. And besides, people have to be responsible for what they do, themselves.
Did I mention "been there, done that myself"? The best assumption is that you're doing it wrong and based on that, critically look for the flaws. I know. I wasted a lot of time *at more than one stage* because I thought I was doing things right when I wasn't.