Well just picked up a 83 s10 blazer & idk the name of it exactly but the shifter for the 4wd selector goes into 4 high with button depressed and neutral.W
hen I put it into 2wd or 2 high it just pushes forward it will stay but the button doesn't really work at all. I drove home 2 days ago in 2wd and it was fine
I just don't know where to start honestly. Any suggestions ?

 

My old 83 and 84 would get mud, dirt even small rocks packed in the shifter shaft binding it - every year or so I removed it and cleaned and oiled it well.

 

 

Linkage should just snap into the rubber groment at the bottom of swing arm from the 4wd shifter and has the same setup on the shift lever on the transfer case.
Also there is a vacuum actuator should have a rubber boot that has 3 lines, vac, vent and vac to front diff.
If boot is disconnected it usually ends up on top of the transfer case or hanging down on the pass side.
If it's not to be found maybe there is a bone yard close to your area that may have one.
Worse comes to worse the lines can be plugged directly on the valve but the boot has a peg to line up the lines and will save on figuring out where they go.