Follow these steps to fix vertical lines on your printed pages:

1. Check Paper Quality: Use only good quality paper for printing.
2. Check Printer Position: Make sure that your printer is not shaking or vibrating
3. Clean Printer: Clean the paper feed roller and other parts of the printer.
4. Replace Printer Ribbon: Replace the ribbon of the printer if it is outdated.
5. Replace Printer Driver: Replace the printer driver if it is not compatible with the latest operating system.