Removing original paper texture from high res b&w scans

[rich2005]

Your sample is a bit small but a couple of things to try.

I would put the image into grayscale first: Image -> Mode -> Grayscale

Colors -> Curves and pull the curve up screenshot: http://i.imgur.com/OmexI8i.jpg

There is a Gimp plugin g'mic http://www.gmic.eu which has a filter Repair -> Repair scanned documents which might give a result  screenshot: http://i.imgur.com/o2NGnRD.jpg