Michiel

I hope I am clear enough my (technical) English is not good

Here you find the partbooks https://www.college-sewing.co.uk/parts-books/durkopp-adler-sewing-machine-parts-books.html but i think you have a change your barrel hook race is threaded on the backside and you can make your adjustment by making turns anti clockwise

I might be wrong but i think i have had a 166 where one can turn the race for the barrelhook to move it front and backwards you could try that….

I think i had some help from the service manual for the adler 366 when I worked on my adler 166

Hook setup is the same as adler 205-102 adler 266 and adler 366 (Part 266 15 on this one) I think the hookdriver act as an needle guard

If I remember correctly, the distance is set with shims