The bad thing about them is getting parts, NO one but WCC has them, if your lucky enough they might have what you need. and they are NOT cheap. I have done a few, never found ANY books on them. You will need a special tool to remove the  holding pins on the joint. VERY had tool to find, I do not know the number, but it is a 6-32 thread , on the end to screw into the pins, then you have to pull them out, with out it you cant get the pins out, you cant take the joint apart. There is also  small metal springs, you have to remove, they BREAK super easy. They are NOT a easy to rebuild, and NO PARTS.