I got a tiny mirror on a telescoping stick and a flashlight, and looked in there with the window up and the door panel off. Looked at the cam type piece that the door latch actuator linkage moves to lock the door from the inside handle. Looks like the "stops" that are stamped into the backing plate type piece of the latch, those have been worn down, and the locking cam was rotated a degree or two too far for the actuator to move it, as it was putting the force onto the wrong part of the cam. Oiled it up and fiddled with it and got it to work most of the time, but I really need to take it out, hit that stop with the arc welder, and grind it back into original spec and shape. Door just wouldn't lock at all from the inside, open or closed. Driver's side has always worked fine. Pass. side exterior lock cylinder still doesn't move at all when the key is inserted. Wasn't sure if this was the "dummy lock" that was mentioned above, or not. Might have to find another that my keyway fits, and get it re-keyed to the rest. barn doors, ignition, and I think glove box all work off the same key as the driver's door. Nice to have.
Is this the case with the supposed "dummy locks?"
Thanks,
Chuck in Ohio
'62 GMC 1000 panel truck 305D (tremec 5 spd/'89 PB discs and PS soon!)
'71 RS/SS Camaro project 406 sbc Tremec 5 spd corner hugger (pile of parts for now)