Doubt you will get one anywhere mate unless someone breaks a box I was looking for one too, early boxes has the clip later had the ball and circlip.

I managed to get the later one and have had to make it fit, they come in a browny colour.

Those pictured look very similar though as long as the ID is the same and amount of splines it will still work, what were they off of?!

Also I doubt it has broken as such just sounds like it has come loose off the shaft so probably the early type you will have to take the end cover off to have a proper look may just need a new clip!! Which are also rocking horse shit