Shank in summer again

Played two rounds on May 25, and shank came again, first at 9th hole, and then became more severe during 2nd 9 of the first round. Since this is not new to me, I quickly checked my previous blog notes and reminded myself to fully extend my arms at the top of back swing. I tried this during the 2nd round, with mixed results: short irons (9 and PW) seem to be working, but mid and long irons still shanked quite often.

Practiced at home, and then went to Glenview for a practice round on Memorial Day afternoon. Again, with similar mixed results -- tend to shank mid and long irons. PW was ok, hit a couple of good 7 iron shots, but all 6 iron shots were shanks. Moreover, I found that I started to hit everyshot off heel parts, including driver, fairway wood, and hybrid.

Read previous blog posts (http://fuzzify.blogspot.com/2013/06/), found this instruction video of Effortless Golf Swing:
http://www.youtube.com/watch?v=jwpdkuC3H_k
and decided to go back to basic easy swing. Tried at Southwest Golf range with nice and easy swings, not much distance. Once started to swing harder for more distance, shank and heel shots came back again for mid and long irons...

Then I searched on-line for how to fix hitting off heels, and found this thread:
https://thesandtrap.com/forums/topic/21152-hitting-most-shots-off-the-heel/
One guy mentioned about head moving towards ball during down swing, and I thought this might be my problem too.

Finally decided to videotape my own swing for some analysis, and then I think I have found the root cause: head lowered or dipped during down swing, or body turn not enough, or even both. Also backswing seems to become flat again.

So checked my previous blog notes again, and make some swing changes:
make sure entire body is relaxed
go back to neutral stance (instead of 55% weight on left foot / deloft clubs)
more upright swing, (3/4 check point), fully extend arms at top of back swing
initiate down swing with lower body (with "go belly button" in mind)

Tried these at Eagle Tee range, and made solid contacts with 9 and 8 irons. 7 iron some good, some not so good. But 6 and 5 irons not very solid... This is similar to what I experienced before:
http://fuzzify.blogspot.com/2013/08/swing-change.html

Maybe just need some time to get back to normal. Meanwhile may need to bring out 7 woods and 4 hybrid...