Sounds to me that is is the lock mechanism itself. If the "button" is raising and lowering when you turn the key, then the horizontal rod from the outside door lock is properly engaged into the door lock mechanism and the vertical rod that goes up to the door lock "button" is properly in place. Likely a spring within the door lock mechanism.
Either way you'll still have to remove the inner window surround, door/window handles, arm rest, etc., and remove the door panel.
I have the other 3 door locks NOS, but not the driver's door.
Good luck...common problem on drivers door...Mike