Thank you for the reply Jiberjaber,
My initial thoughts, after reading up on the various forums, were to glue the plastic together and then reinforce the outside with a two part epoxy. But then I over mixed the filler.
Having read up and a cure is to replace the rod. So the current idea is to drill the back and fit a rod like this:
If I can find a car with a matching ball size.
Or drill through the ball and the base and then thread the bits and replace with an allen bolt.