Door lock problem

[Jakeinaka]

I've read a lot about E89 issues since I got mine to be prepared for any eventuality
So today just out of curiosity I tried the key in the door lock, guess what, no cigar. The key will turn 10~15 degrees in either direction, but then meets resistance. Has anyone had such an issue?
Not an urgency, as remotes are working OK (he says touching wood with crossed fingers). Before I consider tearing the door apart, does anyone know what the mechanism is like? Where can I find decent images so I can figure out what's wrong?

Thanks

EDIT: a few hours before I typed the above, I had squirted some WD40 in the lock. Just tried it, with a little force the key finally turned. Probably the first time in 8 years, so all is well.

As you were!