Thanks verslagen, I had a hard time measuring too, The pointy parts get rounded so it is hard to measure.
I was wondering if anybody here has used loctite 660 on that shaft before.
I can imagine you would put it on both surfaces, slide the pulley on and most of it gets slid off.
Then get washer and nut on quickly and torque it before it sets! :'(
And don't forget to slide the belt on with it!

I don't know if the gap is much bigger than .25mm?
If someone has done this before, please let me know, I did not see it on this forum.
Thanks, Gerrit.