There's a pic in my gallery (thanks if you can stick it here) showing the nut on top of the aluminium seal. I have a feeling this was how it went together. (Unfortunately I didn't get a photo as I was disassembling it 😔 )If I do the nut up tight-ish, it starts to restrict the steering movement. If I do it up just enough to stop the fork wiggling, the rubber seal underneath the aluminium disc is a bit squashed, whereas it wasn't before (see first pic). Do you think this will matter?