The Xeroxes are normally set to scan your original at a default resolution of 300dpi. You can alter this either up or down, depending on the complexity or detail of the original – from the Copy screen, choose the Image Quality tab and alter the settings for sharpness and/or contrast. For originals on non-white or poor-quality paper, you can also choose to activate background suppression, which will ‘wipe out’ any greyness in the background and improve the contrast in your copies.
If you used the document feeder (ADF) and your copy is produced with very fine lines across it of uniform thickness, then the scan window needs cleaning. When scanning through the ADF, the Xerox uses the letterbox scan-window to the far left of the main scan glass, and any debris or specks of dust on this will cause streaks across the copy output (which will not be present if you scan the original off the main glass). Sometimes the debris isn’t visible, but you’ll be able to feel it if you run your fingernail up the glass. Simply clean the glass strip and re-copy.