Just tried to tighten my top-cap bolt, but nothing happened, so I loosened it off to have a look, but now the bolt won’t come out even though it’s turning. Is it possible that the star nut or threaded insert in that is turning? Cheers for any help.

If it’s turning then it must be loose, can you push it up from below with a stick or something? Might need to take the front wheel out.

the threaded inserts can come loose.

try pressing down really hard and turning the allen key at the same time.

if that fails I’d be looking to cut the stem cap off so you can get access to the SFN and superglue/hold the insert in place while you turn the bolt.

Taking it down to the shop tomorrow. I don’t want to mess aroudn with it now because if it is the star-nut, then I might end up scoring the inside of the forks.

Have a look up from the bottom to see if it is turning. I agree with wwaswas, more likely the theaded insert is turning.

if the star nut is turning you will hear it going round inside and will be quite hard to turn.. if free spining and easy then it has gotta be the nut spinning in the STN

I can’t see from the bottom ad there’s a plug thing in there.

take top cap off insert the bolt and see if you can spin the inner bolt /look for wear unless you have some clear hard plastic you can use to tighten it up properly and see what happens.
No way the SFN will free spin unless it has broken splines so you should be able to wobble the whole SFN if that is the issue and see some broken splines