Streak on photocopies but not on prints from computer

[madnessmfp]

My printer suddenly started having a black streak -- only on photocopies, not on things I print directly from my computer.

I've tried all the troubleshooting suggestions and nothing has worked. Please help!

[Repairatrooper]

To narrow down between possible causes, make a copy from the scanner flat glass and from the document feeder. If you get the same issue with both scanning methods then you have an issue with the scanner itself. If the error only shows when scanning from the ADF then there is most likely an issue with the small section of glass that the ADF uses for scanning. This section is covered by a thing plastic sheet that directs the paper into the exit rollers of the ADF. Over time this plastic will get worn from pages passing over it. Often the wear can be so slight that it is nearly impossible to detect. I have also seen cases where debris gets trapped under the mylar. If you remove the mylar you will have to replace it. However if you see dirty under it you can gently pry the retainer from the left side of the glass and gently lift the right left side of the mylar to remove any debris. The mylar strip is glued to the right side of the glass and that is the side you need to ensure does not become dislodged.