Yeah agree it sounds like trigger bar spring unless proven otherwise; last P-09 I did had what sounds like same issue (posted somewhere here and members helpfully pointed out it's a known issue); though I (thought) I didn't mess much with the original spring. After a great deal of swapping parts, trial and error with my other P-09, confirmed it was the problem, though the culprit spring was no different in shape nor in subjective tension on the bar. Got a fresh spring in it and no further issues- YMMV of course.