I’ve reached the point now where I think I have to just trust the muscles of the left hand to know what to do. This has happened a few times in other situations, where I wasn’t sure where to head in the left hand, and had to just gently mull (usually when I’m waiting to drop off to sleep) and observe how my left hand wanted to move on its own.
Playing a lot of good music sort of trains the hands to recognize not just how something will sound but also how it feels to play it. I’m fairly sure that I’m at that place in this second six-flat thing.
I’ve also managed to sketch out a rough idea on how to find my way back to the main theme. I like to go “full circle” a lot, it seems — sort of that T. S. Eliot poem that says something about returning to where you departed from and, thanks to whatever you learned during your peregrinations, seeing it anew and clearly for the first time.