Any question answered...

A few pages back, I posted r.e. a missing split washer in my headset.

Stonehedge gave me a split washer, I put in in - the headset won'e tighten up properly (leaves a gap between upper race and steerer tube). I take it out - the headset wont tighten up properly (wobbles around).

It's one of these Ribble ones: http://www.ribblecycles.co.uk/sp/road-track-bike/Headsets-Ribble-Headset-Branded-Ribble-1-1-8-Hidden-ITS-45-x-45/RIBBHSTR200000000000

Anyone know what I'm doing wrong?

Just in case it's useful for anyone else, I've closed out this issue:

I emailed Ribble and asked if their headsets came with split compression rings. They replied: 'no'.

I bought a new headset from Condor and it came with a split compression ring. The 'ring fitted. Everything, other than the logo on the top caps, is basically identical about the two headsets.

Ribble were telling fibs :-/