On to the disassembly. By removing the nylon snap ring the inner works can be pulled out. This is what you get inside:
And the inside of the housing (showing the actual steering wheel lock deeper down with a spring etc.)
From this I didn't find any loose or damaged parts. What I did find though was grease which has almost turned solid. That's not really nice. Also there is a little spring pin at the bottom of the assembly which I think is the main spring force to keep the key barrel connected.
his pin and spring were also very very sticky. The pin did return, but slowly. So I took it out, cleaned the hole with brake cleaner and did the pin and spring as well. New grease on and re-inserted. I did the same on the other parts (the housing as far as I could as I didn't want to use brake cleaner on that with the wheel lock parts still in place). All new grease and then assembling it.
So far I now can't replicate the endless turns anymore. The tricks I learned to get me into that mode no longer work. Besides that, the wheel lock pin now really snaps out when I remove the key. Previously it would slide out slowly.
Overall I feel this could have solved my issue. I will get myself a new ignition switch as well as the old one does look a bit dodgy, but will keep the whole mechanism and try it out.