Image quality issues can be caused by different things. To find out what may be causing the problem, first determine what process you are using when you see the issue. If the defect is only seen on copies, that is a different issue than if you see the issue only on prints.
If the image quality issue only happens when you are making a copy, the problem may be with the glass that the original travels over to make the copy. Clean the scan glass on the machine if it is accessible.
If the image quality issue happens when you print, try printing an internal report from the machine like the settings or configuration report and see if the defect shows on the report. If the internal report is fine with no defect or error, the problem is with the original file or document. Try printing a different document from a different program to confirm.
You can look up information on print quality issues via online support for your machine. We break down the solutions for image quality issues that happen on copies, prints or both. Sometimes you will see image issues at a regular interval like every 1 inch or some other interval. These, too, are covered in the online support. Another component of image issues is whether they are horizontal or vertical lines, bands, dots, or deletions. See this quick video that addresses repeating defects. This video is for Xerox WorkCentre® 7435/7535/7830/7970i but the steps and procedures are similar on most Xerox printers.
Many image quality issues can be solved without having to make a phone call for assistance. Identify the applicable components for your issue to help you narrow down the potential cause of the image issue, such as what direction it occurs and if it is at a regular interval. Then search for solutions online, follow the solutions steps and you will be back in business.