@uwe
many thanks also to you for the extensive and patient reply
i got the shuttle driver moved farther away (right) from the needle, about 1mm, polished with a felt biffing wheel the shuttle and bobing casing and removed the dragmarks on the shuttle hook, where the thread liked to snag, the overall improvement is marginal. i might consider a new shuttle, bit dont know what machine, which subclass i actually have- does it have to match most of all the shuttle driver ( jimi ruled out other pairments earlier) . how much play does it have normally? right now its about 1,5mm and tilting around the swivel axis is also significant, unable to measure that.
the actual shuttle: