I have a 1970 'Cuda C7, 383 with an automatic trans.
My problem was the same as Sukhoi's,- my passenger's door would not open.
When I looked inside with a pen light everything was working and moving as it should. This lead me to believe that the outer latch was not moving on the post to allow the door to open as it should.
I took a spray can of WD40 placing the nozzle to where I thought that the latch was and sprayed away and luckily it worked.
So I just wanted to say "THANK YOU" to all who answered this older post.