Please try the following and let me know the response.
Caution: Do not use a hard or abrasive brush, benzine, alcohol, or paint thinner to clean the WorkForce 520 Series or you may damage it. Do not use oil or other lubricants inside the WorkForce 520 Series or let water get inside it. Do not place anything on top of the document cover or use it as a writing surface, or it could get permanently scratched.
1. Turn off the WorkForce 520 Series.
2. Unplug the power cable.
3. Disconnect the USB or Ethernet cable.
4. Remove all the paper.
5. Clean the sheet feeder using a soft brush.
6. Clean the scanner glass with a soft, lint-free cloth moistened with a little glass cleaner.
Caution: Do not spray glass cleaner directly on the glass. Do not press the glass surface with any force.
7. Clean the LCD screen with a soft, dry cloth. Do not use liquid or chemical cleansers.
8. Clean the inside of the document cover with a soft, non-abrasive microfiber cloth.
9. Close the document cover and paper support, then clean the outer case with a soft cloth dampened with mild detergent.
Note: Close the paper support and ADF paper support when you are not using the product to protect it from dust.
If you can see the rollers, please clean it using cotton buds.