Can’t get my headset right, it’s either too tight or there’s a little play, there doesn’t seem to be a compromise. It’s greased up and installed correctly…

Suggestions…?

depends a bit what “too tight” involves – if it’s just a bit of resistance, ride it & you’ll get used to it.

Is it new ? – if not, maybe the bearing races are pitted, making it notchy ?

Crown race on properly?
Compression adjuster in properly?
Enough space between the base of the top cap and the steerer so their not touching each other?

It’s worn out.

If not it’s either crap, or your rattle is coming from somewhere else (eg fork bushings).

Definitely not the forks. I’ll have to install from scratch again and see.

Bing some more grease in and see what happens, this is of course assuming that the cups are in straight in the first place

which headset?

Ritchey WCS, never had a problem with them before though.

Is the SFN in straight?

N/A – Mav DUC’s

happened to me too, i reinstalled the cups then it was ok, a friend had an off and that upset his a little but he had to ride home anyway and it reseated itself.

Is it an intergrated headset? I’ve just had trouble with one on my road bike, turns out that you only need very small imperfections for it not to fit properly, tried a different headset and now all is fine.