Door Latch
 

I've got a 1970 Chevelle. I went out to go for a ride yesterday and the driver's door would not open. When I attempt to open the door (either inside or outside) the latch partially releases and the door moves about 1/4 to 1/2 inch, no further. I've tried locking and unlocking with the key and latch. No use. Any ideas to unstick the latch?