You need:
A short piece of metal bar if the same diameter as the projecting part of the joint. I used a 1/4" socket.
An O-ring that will fit the above (or an elastic band). With the socket, place O-ring in, followed by the needles - 28 on my GSA.
Push it all into the Triaxe ball on the inner end until it's flush; the O-ring will fall off.
Then it's just a matter of greasing everything and pushing it all onto the projecting part of the joint.
Make sure it doesn't all fall out!

HTH.