Diff lock woes - not what it says on the tin.

So it would appear that the diff lock on my Disco 1 has never been used for more that a handbag support by its past owners.
Not only does the handily placed little diff lock selector stick not move, it is in what I take to be in the low ratio position (front right), please do correct me if I'm wrong here.

I know the clutch has been replaced before so is it likely that something hasn't been put back correctly and that all the shiny handle is now useful for is the nifty little handbag support it has apparently always been used for until now?

They can be freed up but I have a few spares if needed.

Gosh that would be a slow ride in low range all the time. Easily freed up mate and will slot back in to hi range then and over in to diff lock

Think I should have described that a bit better. It drives like it is in hi range but the selector is very much in the lo range slot.
I don't mind having a go at freeing it off but if something is fundamentally wrong then I don't want to risk buggering it up even more.