First thing: is it still under warranty? If yes, do nothing. Take to nearest service center and "inflate the problem a bit"to ensure they actually attempt to fix it.
If not, then there's a few things to consider. Did you drop or bump the thing? (Prolly not, but worth asking). Does it only make noise when the "reader head" is moving? I.E. scanning? The head is moved by a toothed rubber belt. I may be dirty or loose. If it's not under warranty, open it up and see if anything is loose. The belt should be fairly tight. It may just have dust on the moving parts and that's what causing the noise.
Also check out HP websites: the may have a FAQ on this. Good luck.