If the streaks that are being produced only occur when using the Automatic Document Feeder (ADF) and not when making a copy via the platen glass, the issue is commonly due to small marks or debris on the scanning glass area that lines up underneath the ADF roller. Small smudges on the platen glass can cause "streaks" to be produced as every inch of the paper fed via the ADF passes over the area and is picked up by the scanner. The ADF roller is located on the left and underside of your lid. The scanning light sits in this area when using the ADF.
If it occurs when using the platen glass you will need to carefully and fully clean the glass in the scanning area. There can also be a strip of transparent plastic on which there can be a mark or smudge. Look for scratches, tiny spots and marks of any sort. You can use a soft lint free cloth either dry, or just very lightly moistened to clean the glass. and you may have to scrub (gently) to remove certain types of marks.
You may also wish to clean the underside of the lid.
NOTE: do not spray a cleaning solution onto the glass.
After cleaning the platen glass, run four to five blank/clean pages through to test it and see if the streaks still appear.