Door latch doesn't catch

the door lock and catch probably need adjusting , look for signs on the latch for wear , shiny edges etc , this means the door lock isn't aligned correctly , adjust the latch and apply some grease too

Door latch settings are out because door slamming and abuse of unit

Can you move the latch in the door? This is spring loaded, maybe the spring is broken

Door pins are a common failure on that series of Blazer/S10's. Also, another point of contention that the door faces is a sticky latch. Basically, the door latch re-latches itself and when you shut the door into the catch, it slams into it and bounces off. An easy fix is a 3 part cocktail of brake parts cleaner. Open and shut the latch with a screw driver acting as the catch and your interior door handle a few times. P'Blaster, open and shut the door a few times with the screwdriver acting as the catch. Finally, a good shot of white lithium grease. Open and shut the door with a screwdriver as the catch several times. Once you feel it is un-stuck, actually close and open the door several times. If you notice the door rising every time it catches, you MUST replace the door pins (cheap fix). If the door still has issues, replace the door latch (and since you're in there, do some PM and replace the actuator as well).

Find another 91-95 Park Avenue at your local salvage yard...or call on line or contact to reach on-line salvage yards...you can purchase just the latch...(as you know it is designed to be an automatic pull-down...This is an easy switch out...the latch will be $20-45. I have one at home:) Hope this helps.

Door catches.

If one of the latches has broken off and is not lifting the other latch clear of the housing. Remove from any power source, remove the cover of the cabinet. Slacken off the clamp mechanism and ease the clamp over the guide to allow the door to open. When a new door lever is in place, the door may be easily adjusted by slackening off the screws that clamp the door catch/actuators in place whilst holding the door closed and then tightening the screws. The rear of the door may be adjusted by slackening the lower door hinge screws and adjusting as required.
I hope that helps.

Door switches

If one of the door interlock switches is not switching properly, that can cause the turntable/light to come on even though the "Starts" button has not been depressed due to the wiring of the switches.
Check for faulty door switches and/or contaminated actuators.
I hope that helps.

!st thing to do is to make sure the catch latch on the door is properly lubed.If it is and you still have problems,then the small catch that is on the car,needs to be adjusted.
Open the door and look where the door catch is.On the car.It,s a plate with a u-shaped metal rod.This needs too be moved outwards by about 3mm.It's held by 2 x head screws.They need to be loosened,adjust the plate,and then tightened back up very tight.
If the car door has been opened very quickly by say,the wind or slammed open,then this can alter the door alighnment.
Hope this helps you

The latch may be stuck in the "open postion" you might try spraying some WD-40 on the latch. Try working the handle a couple times.

I'm not sure what you were told but the (knobs) are the strikers. Do the latches in the door line up with the strikers? Do the doors hang straight? You might need to adjust the hinges or the striker. If it all does line up then you might need a new latch.

adjust the slam plate