A customer reports that the output from their thermal receipt printer has vertical white lines.

Comprehensive and Detailed In-Depth Explanation:

Thermal printers create images using a heated print head on specially coated thermal paper. Vertical white lines indicate that part of the heating element is dirty or blocked, preventing heat transfer to the paper. Cleaning the print head (heating element) will restore full functionality.

Option A: Thermal printers do not use ink or toner, so this is not applicable.

Option B: Wrong paper could cause blank output, but consistent vertical lines point to the print head.

Option C: Maintenance kits are typically for laser printers, not thermal printers.

CompTIA A+ Core 1 Exam Objective Reference:

Objective 3.7: Given a scenario, troubleshoot common printer problems.