Sorry, I should have been more descriptive. I guess a picture helps:
http://www.alibaba.com/product-detai...showimage.html
These sort. Encountered commonly on RA axis, worm ends, camera lenses (just a LOT larger than those in the picture of course). No, a circlip plier WON'T do it - snapped every one I have tried.
I guess I have to make my own again