Hey guys - I'm one of the shade tree mechanics that prefers to ask questions for advice BEFORE I go tearing something apart. In my twenties that was the opposite! Here is my issue... on my 1940 120, Passenger door was coming open during driving if the latch was not positively closed to the final notch. The safety notch was not holding the door from opening completely. Not a great feature! I have realigned the upper hinge and now the travel of the door to closing is great. However, compared to the driver side, when you actuate the inside handle to open the passenger door, there does not seem to have the as much resistance as the driver side. Also, if you don't manually work the inside handle from both directions, the latch will stop at halfway and then the door will not shut completely. My first thought was that there is spring that is weak connecting the inside handle to the latch - that might need to be replaced. Or is the latch gummed up and it needs more lubrication to unfreeze the latch? So... Tear apart or keep it together and try a few tricks to free it up? Thanks!
If you have to wiggle the inside door handle to get the tongue all the way out from the latch, that 75 year old grease in the latch is not grease anymore. In this case there are only 2 springs that have to be checked out and neither can be done without removing the door panel. One is the main spring in the latch itself and the other is in the controller that the inside door handle attaches to.. At any rate, take off the door panel and see what is going on, it's not a big deal. Go to my website julrichpackard.com there is a picture of the latch and the spring there. It just might be a lubrication problem. J.