You can rebuild them but the replacements are the newer style & are a big improvement over the original. It is more work to install the changeover the first time but is the best way to go unless you want to keep it pure. You remove the cotter pin & screw out the plug. Then pull the the joint off the ball. Check the ball to see if it is out of round. If it is OK you can put a kit in it. Check the spring, they are often broken. Tighten the screw till it stops & back it out a little to line up the cotter pin hole. Some had a metal band around them but most are just open.
