Last night, I tried to practice with a new technique from Ron's tip.
A significant improvement was I could grip the ball firmly during the whole swing with flat/cupped/cocked wrist and dropped only a few time, however I could not make the release consistent (of course, it was the first time, what do you expect???

).
The release was too late or too early, or sometimes I still pulled the ball. But when the release was correct, I didn't fell the pull of the ball weight on the fingers (or just felt a bit), the ball looked like just escape from my hand, landing smoothly on the lane (no sound), and it rotated a lot (even with small angle), and it hit the pin very hard. It happened only probably 1/20...
I also got problem to hit the target... a year makes sense now...