copies come out with black streaks and smudges down the page on my brother mfc-j1010dw

Diagnosis

When your Brother MFC-J1010DW produces black streaks or smudges specifically during copying or scanning—but not when printing from a computer—the issue is not with the ink cartridges or print head. Instead, the problem lies within the Automatic Document Feeder (ADF) scanning path. The ADF uses a small, narrow strip of glass (the platen glass) separate from the large flatbed. When a page is pulled through, it glides over this narrow strip; any speck of dust, dried ink, or correction fluid (White-Out) trapped on that glass creates a continuous line of "debris" as the scanner sensor moves, resulting in a vertical streak across the entire length of the page. To confirm this is the root cause, perform a "Flatbed Test." Place your document directly on the large glass platen, close the lid, and make a copy. If the copy comes out perfectly clean, the large glass is fine and the print head is functioning correctly. If the streaks only appear when using the top feeder, the narrow ADF glass strip is contaminated or scratched. Because the scanner reads the page as it moves, even a microscopic dot of ink on that specific strip will be interpreted as a solid black line on the final output.

How to Fix It

1. Lift the scanner cover to expose the large flatbed glass.
2. Locate the narrow strip of glass situated to the left of the main platen glass. This is the ADF scanning glass.
3. Dampen a lint-free microfiber cloth or a cotton swab with a small amount of isopropyl alcohol (70% or higher). Do not spray liquid directly onto the glass to avoid seepage into the electronics.
4. Firmly wipe the narrow glass strip from top to bottom. Pay close attention to the very edges where the glass meets the plastic frame, as ink often builds up in the crevices.
5. Lift the document cover (the white plastic underside of the lid). Inspect the white backing strip for any black smudges or ink transfers. Wipe this area clean with a damp cloth, as dirt here can cause "ghosting" or grey shadows on the page.
6. Use a dry microfiber cloth to polish the glass and remove any remaining streaks or alcohol residue.
7. Load a single sheet of plain paper into the ADF and run a test copy to verify the lines are gone.

If That Didn't Work

• Clean the ADF Rollers: If the smudges look like "tire tracks" or irregular blotches rather than straight lines, the rubber pickup rollers are likely dirty. Open the ADF cover and wipe the rubber rollers with a damp, lint-free cloth to remove paper dust and ink buildup that may be transferring to the page.
• Check for Glass Scratches: Inspect the narrow ADF glass under a bright light. If you see a physical scratch or pit in the glass, cleaning will not work. In this case, the scanner assembly (the CIS unit) must be replaced, as the scratch is being read as a black line.
• Perform a Hard Reset: Occasionally, the scanner calibration can glitch. Unplug the power cord from the back of the MFC-J1010DW, wait 60 seconds, and plug it back in. This forces the scanner head to re-home and recalibrate its zero-point.
• Update Firmware: Check the printer settings menu for a firmware update. Brother occasionally releases updates that adjust the scanner's image processing algorithms to better filter out minor debris on the glass.

Heads Up

• Avoid using paper towels or tissues on the scanner glass; these are abrasive and can create micro-scratches that permanently cause streaks.
• Never use glass cleaner containing ammonia or bleach, as these chemicals can strip the anti-reflective coating off the scanner glass.
• If you frequently scan documents with correction fluid (White-Out), wait for the fluid to be 100% dry before feeding the page through the ADF to prevent it from peeling off and sticking to the glass.
• Periodically clean the ADF rollers every 1,000 pages to prevent paper jams and "smudging" caused by slipping rollers.