Shimano DX cassette hub help

[generallee]

I hve a nos set of Shimano DX hubs, the old 80s type with the cassette hub rear... I have the plastic spacer, thenthe cog, and then a metal circlip / split ring thing... anyone give me any tips on how to fit it ? I know it's plastic sleeve, then cog, then clip - but the clip is TOUGH to work out!
any help appreciated!
steve

[mark 2]

They're a twat to fit Steve, try and hold it down with your thumb on one side and about a third of the way around prize it open with a screwdriver and lever it downwards and further around.