I just went through this on the 48. I replaced both springs in the drivers door latch, still have the passenger door to do. The handle was sagging down over half way, now it is up where it should be. There is a very small amount of slack or play due to the latch wear over the years. Others on this site didn't recommend twisting the shaft.
What I did was remove door and window handles, then the door panel and then the door latch itself. Then carefully opened up the latch mechanism and installed a new spring. I then reassembled the latch. It's a tedious process. I know there are other methods such as literally twisting the square rod that the handle fits onto. Drake has new springs.Read all the following and put an ad in Wanted section.
https://www.fordbarn.com/forum/search.php?searchid=9740820
Check Ebay:
https://www.ebay.com/sch/i.html?_fr...ch.TRS0&_nkw=1940+ford+door+latch&_sacat=6000