BE1 clutch fork ball-joint

[davemar 16]

I'm just in the process of doing the clutch change on the car, and noticed the clutch fork arm (the one that slides the release bearing on the shaft) was very slack on the ball-joint.

The plastic socket in the fork arm (that the ball-joint pops into) was very tired, so I've bought a new plastic socket. Trouble is I don't know how to secure the plastic part to the arm. There's a couple of little cylindrical lugs that go through a couple of holes (about 3-4mm dia) to locate it; but nothing to seemingly secure it place? Any ideas?