Driver's door locking 89 S4

I cannot lock my drivers door with a key. I can lock it manually from the inside using the associated locking knob. I can lock both the drivers and passenger doors simultaneously using the key on the passenger side when both doors are closed.. I also can lock both doors from the inside with the dash central locking button. What is my issue with using the key on the driver's side key lock?

nluk100 wrote:

Either the lock has seized or it's been changed and your key doesn't fit correctly. Doesn't take long to whip it out and take a look at it, only 1 bolt holding it in.

I don't believe the lock is seized because it operates to open and close using the passenger side key lock, driver's manual turn knob and the dash console switch. It is just when I use the driver's side key lock that it doesn't lock. Your suggestion of a changed lock might be the answer.

I removed the lock after referencing the aforementioned ( www.928.org.uk/56-re-keying-porsche-928-locks.html}. Process was simple until I got to the point of pulling the lock assembly out of the door. Since my 89 had the alarm function, the alarm wire length was too short to pull it out completely to access two tiny screws holding the nylon block and wires attached to the end of the lock assembly. Had to use a small 90 degree Phillips screwdriver at a tedious angle to detach it without scratching the door paint. If you car is without the alarm feature, you wouldn't have this problem! After taking the lock apart, it revealed that one of the small lock blades was corroded and slightly bent in a blocking position, thereby refusing to allow the full key insertion.. Removed the one problem blade and was able to insert the original key with full function. Now the only issue is, that a possible thief now has one less of the 12 blades to pick!!