We get several service calls a month for “black line (or lines) on copies” when customers are using their copier/scanner/MFP to make copies using the document feeder. The customer’s print jobs do not have these lines. Most of the time it’s a simple fix. To trouble shoot the problem place a clean document on the original glass and make a copy. Next make a copy of the same document using the document feeder. If the line is only apparent when copying thru the document feeder you will need to clean the scan-thru glass. The scan-thru glass is located next to the original glass and is much smaller in size. Usually the “black line” culprit is ink or white out adhered to the scan-thru glass surface. Clean the scan-thru glass with a paper towel dampened with glass cleaner or alcohol to resolve the problem. Another great glass cleaner is denatured alcohol available at most hardware stores in the Houston area.