Liquid plastic (interested that's all)

[Marvo]

We get something called copper reducing links which are basically a reducing ferrule and would work to replace that broken plastic part. I can't find a UK supplier though. You'd need to heat up the nipple and pull it off first then refit it using a solder pot afterwards. It's a lot of messing around to save a few quid though Tel.

**edit** Here's something similar Copper Round Pin Terminals - Cablecraft - http://www.cablecraft.co.uk/copper-pin-terminals.html
You could maybe try slotting one with a dremmel tool rather than removing the nipple.