After scan is complete, I have black thin lines running from top to bottom on the entire sheet.

[Robert2323]

I have thin lines from top to bottom of scanned sheet.  Scan is good but thin lines are not needed.  Printer works fine etc.

[Dragon-Fur]

@Robert2323 

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If there are just a couple (or a few) lines, it might be "dirt" or tiny spec of dirt in the glass or along the edge.

Use a flashlight (torch in the UK); shine the light at an angle along the glass.

Clean, clean, clean.

Use a tiny brush to sweep all along the edges of the glass.

and / or

If the lines are numerous, perhaps obscuring the scan, there might be something else going on...

Known solutions, presented in the order to be completed / considered:

Improving Scan Quality

and possibly

 Resolving Copy Problems

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