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Yep, it is a common problem. I imagine that it's almost impossible from the outside, because you have to push so hard and what causes that is that the lubrication that made all that stuff work all snickety and nice, is now 35 years old, gummed up and hard.
The solution is to carefully pull the door panels off and lubricate the mechanisms underneath, including under the door handle on the outside (tricky, but doable with a long zip tie, with grease. I recommend first, cleaning it out with WD-40, before you lube. And you might want to vacuum the bottom of the door while you're at it. A lot of dirt collects there too. And, while you're there, get the power window tracks, because they need lube and love too.
PS: You can adjust the force it takes to open the door, by adjusting the hooks on the end of the actuating rods.
adjust the door handle linkage from the door handle to the door lock mechanism.I would turn it out one turn. I had the same issue and this is what fixed it.