Hi Thomas

I'll answer in English because it is much easier for me to type.
These bolts were also very stuck for me. After spraying with WD40, I used a 1 inch ratchet with a 1.5 meter bar and then still had to pull with 2 people to make the nut come loose.

Try to clean the threads very well because on mine the the threads on the bolts had filled up with rust.

Greetings,
Klaas