Update:Had a lesson yesterday--big improvement
It turned out that Harry needed stronger cues from me. It was as I figured, that I was passengering EVEN WHEN I thought I was riding better. Better...but not enough.
I'm not very strong because of several physical challenges so what I thought was maximum effort for me was still without direction for him.
So correcting him is now coming from my legs, seat, core and upper body. WOW...lots of hard work. He tried today to follow daughter's horse but soon quit when I applied enough leg. Even made him change rein @ x on a reversal. So exciting.
We decided I should just walk/jog and work on those transitions until I remember what to do and get stronger so it's not so hard and painful for me.
I had a wonderful lesson ride yesterday and another lovely practice ride today. Practiced upward and downward transitions and halt with core and seat. A-mazing!!! Turns out my 'clunker' is really a Rolls-Royce! Love it!