It's been a while since I've provided an update.
Since I last posted, I have had lessons with an APA SL7, which provided a modicum of insight and at least a few exercises to try, and an SL9, whose input was eye-opening.
In the interim and with these relatively inexpensive lessons, I've been able to learn how to align my body to the shot much more consistently and appropriately. Between the drills the SL7 gave me, and the insight into my particular issues the SL9 gave me, I have dramatically improved my game.
Last Wednesday in league, in my first match of 9-ball, first rack, I lost the lag. My opponent made a ball on the break, then missed and gave me the table. I ran out the remaining 8 balls. I NEVER DO THAT!!!! I won that match (SL4 v SL4).
In my 8-ball match, I won 3 racks to 1 (SL4 v SL4).
The keys to my recent success and confidence:
1) My stroke is so much straighter now. Using one of the drills the SL7 coach gave me, combined with the stance and tweak of my elbow position (moving it a hair away from my body) have enabled me to stroke SO MUCH straighter than I ever have.
2) My stroke is straighter because of alignment mentioned in 1) above, but also, the SL9's mantra with nearly every shot he watched me take in our 2-hour lesson: relax and stroke it.
So I now have two keys to MUCH better potting percentage: 1) keeping my elbow up (I quit dropping it) and 2) keeping my right arm and grip TOTALLY RELAXED. I cannot believe the difference these changes have made. I can make looooonnnnnnggg shots with confidence now, at various speeds. The difference to me is stunning. Now, when I miss, it is nearly always because I squeezed the cue, or I dropped my elbow. I can shoot what used to be difficult shots with follow or draw, and be pretty confident the OB will be pocketed, which has allowed me to better focus on speed and angle the CB will take, which then has made subsequent shots easier, which instills even more confidence and relaxation.
I can't say I'm "fixed" but I'm playing better than I ever had. I simply need to remember three things: 1) Are you aligned correctly and have you truly selected the correct shot line? 2) Keep the elbow 'quiet'. 3) (Arguably my most impactful revelation) RELAX YOUR GRIP AND FOREARM AND TRUST YOU ARE ALIGNED, STROKE STRAIGHT THROUGH YOUR AIMING POINT.
It's so gratifying to finally approach a table without the dread of how I'm going to screw up, and hit balls with confidence. No, I don't run out often, but at least now it's actually feasible, while three months ago I was lucky to make a three-ball run.