Truss rod at end of adjustment

Hi all, This is my first post here and I hope someone can give me some ideas about the problem I have.

I have a Lowden 035. It is approximately 10 years old. I recently took some excess relief out of the neck and it is just fine at the moment with just a little relief. At the moment I am very happy with the feel and playability of the instrument.

However, when I tightened the truss rod it seemed to tighten up to a point and then allowed no further adjustment. I did not force it but I am certain that it will not tighten any further.

My concern is that down the road a bit I may need to make another adjustment. How can this problem be remedied with out major surgery such as removing the fretboard/neck etc?

Any ideas would be most welcome.

Steve