Diagnosis
Accumulated dust and debris on the acoustic fabric. Do not use liquids or vacuum cleaners directly.
How to Fix It
Use a soft, dry microfiber cloth. Gently wipe in one direction. For deeper dust, use a soft-bristled brush like a clean paintbrush or a dedicated electronics duster. Brush gently across the fabric.
If That Didn't Work
For stubborn spots, slightly dampen a corner of the microfiber cloth with distilled water only. Wipe gently. Never spray cleaner directly onto the grille. Let it air dry completely before use.
Heads Up
The grille is not designed to be removed by the user. Attempting to pry it off will break the plastic clips and void your warranty. Clean it in place.