Vertical lines that run in the scan direction usually mean something in the optical path is dirty or contaminated, rather than a problem with the photo itself.

Based on the answers, the most likely causes are:

• dirt on the scanning unit optics
• dirt or moisture on the scanner’s white calibration strip
• a glass or internal part reinstalled in the wrong orientation after disassembly

The calibration strip is a very common cause. If it got dusty or wet during cleaning, the scanner can miscalibrate and produce dark vertical banding. If you used liquid cleaner near the top edge of the glass, moisture may have seeped under the plastic and onto that strip.

What to do:

• inspect and gently clean/dry the white calibration strip
• check the scan head optics for dust on mirrors, lens, or light guide
• make sure any glass or internal parts were reinstalled exactly as originally oriented
• avoid spraying cleaner heavily near edges; apply to a cloth instead

If careful cleaning and drying do not help, an internal optical component may still be contaminated and require deeper disassembly or service.