NOTE: Illustrations shown below are from the representative product and may differ from your Brother machine.
Turn off the machine's power switch and lift the document cover. Clean the scanner glass and white plastic and white film above it with isopropyl alcohol on a soft lint-free cloth.
For the models with ADF (Automatic Document Feeder):
In the ADF unit, clean the white plastic bar and the scanner glass under the white bar with isopropyl alcohol on a lint-free cloth.