For most flatbed scanners, the only user-cleaning that’s generally considered safe is removing the top cover and cleaning the underside of the glass. How the top comes off varies by model, so look for model-specific instructions before opening it.

A cautious approach is best: clean only accessible glass surfaces and avoid touching mirrors, sensors, or other internal optical parts. Those components can be damaged or misaligned easily, and trying to clean them may do more harm than good.

Use non-abrasive cleaning materials intended for optical or glass surfaces, and work carefully to avoid introducing more dust or scratching anything. If the problem is deeper in the optical path, professional service would be the safer option.

In short: yes, opening the scanner to clean the underside of the glass is often reasonable; no, it’s usually not wise to “mess with anything else.”