I have the very problem you mentioned, the top end of my NST is a bit "loose" in such a way that I have to press (and keep pression) abow the "nook" word to have the touchscreen working properly. My solution so far is to use a clip to keep the region squeezed.
Is there any fix?
I've been playing with my problem Nook and I've gotten it a lot closer to working.
The mechanical alignment of the components is very critical.
It's all held together with double stick tape.
Especially the top end is sensitive, that has the biggest span of plastic in the IR (internal) bezel.
But I don't think that this is your problem.