What's up with my door lock?

[71CHEVYSHORTBED402]

The RH door lock assembly works like it's supposed to (locked/unlocked) when the door's open.

When the door is closed it doesn't work. Even in a locked position, simply pressing on the exterior door handle button unlocks the cylinder. That and the cylinder is real touchy (locked/unlocked) when trying to lock the door with the door closed.

Cylinder pawl is between latch fork, I don't see a problem. Perhaps it's a bad latch?, hmmm.. Thanks for any suggestions.

Edit, if a worn latch is the culprit, does anyone recommend a good replacement that's black or even better phosphate like the old ones? Good chance I'll look for NOS, but OER possible. Thanks