Hi everyone,
thank you very much for the suggestions and ideas, you are a great help.
Some details and replies:
I am playing 15 lbs. balls, mostly with thumb slugs, and they fit perfectly. I shrug from having negative thumb pitch - I tried ball of a friend but was not able to hold it, it just slipped off (I have quite long and sleek fingers). I am sure it is not a ball problem, just my wrist bending too much and me getting used to it - rather something mental and a bad habit, yes.
I got in the meantime advice from local senior players, even a national team player (Yeh, that's service...). They confirmed independently that I tend to grip too tight to the ball. Timing and anything before my release is O.K.
A lighter ball won't do; I tried this, but I throw 14 lbs balls halfway down the lane, due to gripping too strong & long. And it does not feel good at all, the 15 lbs is really perfect.
I have a WristMaster II device, and I have tried it in recent trainings again. Have to get a feel for this, but it seems to help, keeping my hand straight.
I also settled for a larger wrist support now, and I tried to open my hand/thumb earlier, so that the ball "falls" onto my fingers as it should. This also feels... unusual, but works fine so far and my results did not drop.
Thank you very much again, and good bowling!
PS:
The M series BMW might be difficult, though...
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DizzyFugu --- Reporting from Germany
"All that we see or seem, is but a dream within a dream..." - Edgar Allen Poe