FSA orbit mx headset, expander how to use and put back

[samsbike]

I know, silly question, but I have this on a bike and I when removing the expanding bit, the whole thing came out.

Now I thought thats fine, just push it back in, but I cant seem to figure it out.

The top cap seems to screw on the expander bit and then the expander gets tightened with the allen key.

However, when I put the bars and spacers on, I cant detect any compression, like you get when you screw in a bolt into a star nut. There is a star nut in the fork steerer, but I am not sure this screws into it or not, or whether it should.

So, in a roundabout way, what do I need to do to put it all back together?

thanks