DIAGNOSIS You can't directly access the impeller blades for cleaning. Dyson doesn't design these for user disassembly, as it's easy to unbalance the fan.
FIX The intended cleaning method is to use the machine's own airflow. Set it to maximum speed (10) and let it run for an hour in a well-ventilated room. This can help dislodge and expel loose dust from the system. For the exterior loop, use a dry microfiber cloth—don't use any liquids, as they can drip into the motorized components.
IF THAT DIDN'T WORK If you have visible debris stuck to the blades that airflow won't remove, or if there's a persistent odor, the issue is likely deeper inside the sealed airflow path. This requires a professional cleaning by Dyson.
HEADS UP Do not attempt to pry open the loop amplifier or remove the grill. You'll void your warranty and risk seriously damaging the delicate, balanced impeller, which will cause permanent vibration and noise.