Because the smudges are not in the original document, CompTIA A+ troubleshooting logic indicates the problem is occurring inside the print process, not in the application or file. For laser printers, smudging commonly points to an issue with the imaging components—especially the drum/photoconductor unit (and sometimes the fuser). A+ Core 1 (220-1201) printer troubleshooting emphasizes starting with the most likely, easiest-to-verify causes before replacing parts. Inspecting the drum is a diagnostic step that can reveal visible defects such as scratches, toner buildup, contamination, or worn surfaces that cause toner to transfer incorrectly, leading to streaks or smears on output.

Replacing the toner (D) is a corrective action and may be unnecessary if the drum is damaged. Changing paper type (A) can help with some issues (like poor fusing or humidity-related problems), but it’s less directly tied to consistent smudges caused by the imaging process. Firmware updates (C) are rarely the first step for print-quality defects; they’re more relevant to compatibility, bugs, or feature issues—not physical smearing. Therefore, inspecting the printer drum first best matches A+ methodology and common laser printer failure points.