Just to clarify the purpose of the door check is to keep the door from swinging too far open and denting the sheet metal or cowl area in front of it.
On the door hinges you will find what are called Spring Detent Plates. One set holds the door fully open the other set half open they come in right and left and upper and lower hinge kits. I don't know if they are available for 1948 vehicles? On a 41 these can only be installed with the hinge off the car and they are riveted in place. I have 4 extra hinge sets and all have the spring detent plates broken. Working on the hinges will necessitate removing the door. While most can find a way to remove a door few will have the skill and patience to reinstall it and align it correctly. I recommend tackling door projects only after memorizing the manual and as part of body restoration.
I have pictures and a video to get most through the project but caution the few "brave and the strong," who take on the project. Having a body shop door hanger would be the ultimate aide, I used an engine hoist with a load leveler.
Good luck, Mike
Description: Door hinge with replacement spring detent plates front view
Description: Back view of hinge
Description: Broken spring detent plate. Each hinge has two, one holds door all the way open the other half.
Description: Check link
Description: Check link attached to door pillar
Description: The purpose of the check link is to keep the door from hitting the cowl
Description: Check link is installed inside the door