Hi,

There is a speck of dirt on the scanner glass under the ADF.

You need to clean the glass (or sometimes it’s a plastic strip) of all dirt and grit.

It is not the main sheet of glass used when using flatbed scanning or copying.

I couldn’t find a video for your particular make and model printer but here’s a video that shows where it is located in most printers that have an ADF. (Shown at 1:02 minutes into the video)

Hopefully it is of some help.