[Dominik]

Yes, in 2000 I also had few problems with TRIGO. Do yourself a favour and clamp a threaded stud (main bearing stud?) or cut off bolt into a drill press or lathe, thread a pin drive over it and spin it.

Then you can get a first indication if it's true (parallel).

The taper is another issues. Wrong angle, and it's not done on a lathe, rather "hammered" on. (the pins get hammered in a mandrel, and not necessarily straight.) Those don't need to be straight where they are meant to be used.

Some adapters also seem to feature 90 deg taper, others 60 deg.