It was indeed how the balls and springs are set.
I was very careful in making sure the grinder seared correctly, but even so, the balls tend to move a bit and drift off the seats.
when they stay it place, tightening the screw is fairly easy. Not so tight.
I reassembled several times until it felt easier. Once I got it right, the grinding was perfect and has been since.
if I ever disassemble again, I will note how deeply the grinder is set in the frame and insure on tightening that it is sitting identically.
I removed the burr grinder. when I replaced it the coffee is always very fine…
Is there something I could have put back incorrectly?