In the second vid we can see that the #1 slide had become disconnected from the actuating bar. None of us have any idea how that could have happened. The set bolt was in a tray I keep on the workbench for misc bolts. It would have required removing the cap, held by 3 screws. Once threaded in, number 1 was synchronized with 2,3,4, working as it should. That would explain why the last dyno run was 2/3 of what I expected. It would also explain why the compression was so low. It wasn't getting any air to compress!
Man, that will go down as a mystery of the ages. I'm thinking it had to do when I was prepping to send them out for cleaning, then decided not to. Just spec, I have no memory of removing it.
I almost didn't post this,as it is way embarrassing. But, that's one of the privileges of old age, no shame.