Vertical color banding on a flatbed scanner like the Epson V370 is usually caused by a calibration problem or contamination in the optical path. Common causes mentioned were dirt on the glass, the white backing/mat, the calibration strip, or the sensor, since the scanner relies on calibration to correct for pixel-to-pixel sensitivity differences.

If you haven’t already, power the scanner off and carefully clean the glass and white reference areas exactly as the manufacturer recommends. In at least one reported case, dust on the glass caused a colored line and cleaning fixed it.

However, if the banding persists after trying different software, a different USB cable, and thorough cleaning of the glass, calibration strip, underside of glass, and sensor, the remaining likely cause is a hardware fault. In that case, there usually isn’t a practical user fix, and professional repair may cost more than the scanner is worth.