The passenger side rear ddor will not open from.

The passenger side rear ddor will not open from insie or outside. Non-electric doors/windows. The door lock button on the top of the door is stiff to go up and down. This door is rarely opened. I sprayed WD-40 along the door jams inside and outside, but no improvement. There is no child-lock mechanism in this car.

I believe this is the same problem that other Corolla owners are facing according to the questions I have read on this website.

I assume I will have to purchase a new interior door latch. And have the interior door panel removed.

Please advise. Thank you. Considering the wonderful service I have received fromt this '94 Corolla, which runs very well and looks great for tis age, this drawback is not too bad.