NAPA NB43 rebuild:
Here is the repair kit for the NAPA NB43. One end of the spring has a loop, which you can see, and the other end is bent at 90 degrees, which is tough to see in my picture. I got the body for free and the kit was $10.69 at NAPA.
The instructions say to assemble things as you see here (NAPA side up), and then you are to align the little post on the selector cover so that once it is in place and you turn it to the left, it engages the spring. At that point, you insert the center screw most of the way, turn the selector to the right and tighten the screw (T-15), and you're done. The problem is that it is a blind procedure once you get the cover near the target.
I made several attempts at that method without success. Then I took the spring out of the ratchet head, placed it in the correct position on the cover plate and, as I peeked through the center hole, I lined the 90 degree end into the pawl hole, then turned the plate to the left as the instructions say, then to the right and then tightened the screw. I got it all done on the first try by this method.
The instructions also say to carry out the assembly with the logo side up; and that would be the "NAPA" logo, not the "NB43" stamp. They are serious about this. Of course my first mistake was to try it upside down. Everything seemed to go together ok, but when you tighten the center screw, the selector won't turn. Assemble "NAPA" side up, no such problem.
The instructions also seem to be very serious about lubrication, it says, "Ratchet mechanisms should be cleaned and lubricated with SAE 30 oil. Never use a heavy weight grease."
Here's the finished product.