Reddit reviews Advanced Karate-Do: Concepts, Techniques, and Training Methods

Some people have posted second-by-second breakdowns... I'm far too lazy for that... er.... I mean, I try to confine myself to correcting one thing at once. Yeah, that's it.

What jumps out at me is that you are leaning forward. Not a little bit, but a lot. This breaks the mechanical linkage of your arm movements to your center of mass, which is why you have the appearance of being "arms-only" in a lot of what you are doing.

The major point of sanchin isn't to make loud breathing noises. It's to control and time tension and relaxation of abdominal muscles, and holding and releasing abdominal pressure. None of which matters for a fig if you aren't mechanically linking those arm movements to what you are doing with your body core.

I suggest consulting this book for more details than you ever imagined existed.