Daytona Door lock mechanism

Is the problem in the door latching, locking or perhaps both ?
Is this a recently developed problem or has it been present always/long time ?
While the basic operations of these components are relatively simple, their adaptation for the application is rather crude and therefor can lend themselves to several failure/problem potentials and only way to figure out the cause(s) is to pull the door panel and look inside.
As far as I know or have seen, unless subjected to some unusual abuse or neglect, just about everything inside the door is repairable.

 

I replaced the outside door handles on my C4 and thought the latch mech was more complicated than it should be. Hardened white grease prevented them from working smoothly and caused the driver side lock to hang up. After a good cleaning and oiling I was able to make a few minor wear adjustments so it works like new. Comparing the mechanism in both doors helped in figuring out how everything worked. The handles were pitted and needed replacing but it ended up being a 10 hour job.