MF634CDW Blurry Streaks on one side when scanning or copying duplex

[davereit]

Suddenly, with no changes on my part, my duplex scanner/copier will not produce clean copies or scans on the back side of docs. I have cleaned all the glass and can't find anything that would explain the problem. Sample of bad scan 

Another sample of the bad results 

Running Windows 11 on a Dell, but this result has no connection to my PC as it's just occurring on the printer.

[Hector]

Hello, 

The images look like the feeder needs to be cleaned or there is something wrong with hardware. In this situation, you can try manual clean the rollers and then preforming a feeder cleaning using the steps in the link HERE. If you still continue to have issues, it looks like the scanner needs service. You can check your available service options from your MyCanon account or by contacting support over the phone at 1-800-652-2666.