The driver side door on my pickup will not open. I took the door panel off and confirmed all the linkages are connected and operate as expected. I took the panel off the other side to observe how it looks when operated. From this I selected a spot to pry with my big screwdriver, this was enough to get the defective latch open. It worked once, anyway. While it was opened I cleaned it out with aerosol brake cleaner and applied some new lube. I was exercising the cleaned, lubed latch with close, open, close, open, close, open, close… no open. Knowing where to pry, I went back in with my screwdriver and now prying in that spot no longer has the door opening like it did the first time. It’s almost like the door is “over-closed” if that’s a possibility. Has anyone had success fixing a similar situation or any advice in getting the door open?

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1975 Dodge D100 225 c.i., HEI, Offenhauser Four Barrel Intake, Parallel-mounted 500 CFM Edelbrock, Split Cast Iron Exhaust, 904 auto, 9.25" 3.55:1

If you have any full synthetic oil for locks or mechanisms give it a try and apply at all areas possible. Zmax is a great full synthetic oil. Pricey, one bottle for engine and a big bottle for fuel (thinner oil)these both last a long time if put in a dropper or precision oiler pen to reduce waste. I rehabbed a non working lock and sticking door and creeking doors all with great results.For sticking door passenger mechanism with a combo of silicone spray and White lithium spray for all metal parts. My trunk hinges and door hinges were all long neglected over time and had old oil and grease making everything sound decrepit. The turning gears on door mechanism that latch clicks into when door closes had lots of old grease and dirt upon inspection. Using the spray can little nozzle plastic tube helps put lube on this. Both sides help.

My door still jams sometimes but rocking car or shaking door relieves this. Not happening much but for a car sitting idle overca long time is doing quite well. My door lock worked barely at first. Then eventually works buttery smooth with a reassuring click in place.
Try a lithium based lube spray and or silicone at first. This helps free up old hardened dirty grease everywhere.
Followup with full synthetic oil which soaks into metal parts for micro lubricant and does not easily attract dirt.
You'll over time have a dependable door and latch with these upgrades on modern oils...
Just be patient your working against decade of dirt and funk..
Good luck.

The problem isn't lack of lubrication. And it's not that you used this lube instead of that lube.

You've got a worn-out door latch on your 51-year-old truck. Find a less-worn one and install it.

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

dan's answer is the correct answer, but if you are dead set on keeping your original latches......ultrasonic cleaner with some good cleaners will clean the internal nooks and crannies. Using it with rust dissolving chemicals will remove any built up rust causing friction points internally. After cleaning with ultrasonic you could dunk the part in any lube of your choice, but if it is at the point of being jammed you have likely already bent links/levers with prying them.

At first I guessed the parts would be '72-'93, but no such luck. '72-'80 for sure, might go as late as '84. '85-'93 for sure, might go as far back as '81 (the question is whether '81-'84 is same as '72-'80 or is its own group).

These dudes are not cheap on Fleabay! Lookit this and this. That makes sense, given scarcity by age and the fact that the driver's latch sees much more wear and tear than any other.

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

My driver door takes a little more oomph to close it properly.
I need to inspect and clean latch and locking turning gear and oil them before committing to a new mechanism or hinges. My car's rare and replacement parts will not be easy to get..

I doubt you have overly firm/tight door seals so your oomph is actually a bad thing.

Hinge pin kits are NOT expensive and even if they don't interchange with almost every other chrysler product a competent machinist could make a bushing/pin combo that would work in about 10 minutes. If the hinges are in good condition then you need to adjust the door correctly.

Watch the door as you slowly close it, if it goes up as it closes you need hinge pins.

Thanks mcnoople,
I figure it was something as a sign of wear as the passenger door doesn't suffer from this.
I'll inspect it on closing and see what it does.
Thanks again

Im redoing an 83 d250 from the frame up and have 3 sets of dismantled door hinges here, all sandblasted and powder coated, ready to be put back together. On all the bottom hinge were shot. 2 sets were from 90-91 model trucks so being yours is a 75 id be surprised if yours weren't shot.
I don't remember if it was a bodies or b bodies that were supposed to be the exact same hinge. But one or the other is.

Also while I was at the Indy swap meet a month ago I picked up a brand new NOS lower one for a newer version of those trucks that's marked either 91 or 93 on the hang tag. I believe these were the same 72-93 on both trucks and vans

So is there any new reproduction door hinges made from A bodies onward??