One of my interior door handles no longer operates the door latching mechanism. I can open the door using the exterior latch. Can someone point me in the right direction for a DIY article on how to fix the non-functioning interior handle?

Remove the door latch assembly from inside the door. Soak and clean 40 yrs of white grease off of it. Lube and reinstall.

Thanks for your response. But, isn't there a pull rod that connects the interior door actuator with the door latch? I can pull the interior door lever just fine; however, that does not translate into any action at the door latch.

+1
While it's soaking I also spray the little nooks + crannies with carb cleaner, and use small brushes, pipe cleaners to get the moving parts degreased and clean.

You need to take it apart and examine it. One of mine quit working and the metal casted hinge was half cracked and broken. The parts are not repairable. Chances are you will need a new one unless the rod has popped off. There is a little metal clip that holds the rod on. Look down inside the door if its not on the rod.

Everything happens at the latch.
Outside handle pushes from the top.
Inside handle pushes and pulls from the bottom.

Click to view attachment

take door panels off both doors and compare.

And I agree with above. They're isnt an moving part on our 40 year old cars that cant benefit from some lube.

I cleaned mine (it was funky) and still could not get it to operate from inside. It almost seemed like the rod was "stretched" and didn't have the travel needed to unlatch. I put a small bend near the inside handle to shorten the rod and it works great.

If you've just recently had the door panel out, you swapped the screw for the door latch surround with that for the window crank. The window crank one is just slightly too long and will not let the handle move enough to open the door.

Check that first.

--DD

Dave is correct. If the screw is too long the handle won't release. I had this happen to me the first time I took my panel off. Drove me nuts trying to figure it out. I won't tell you how long ago that was...