Blockage, full bin, or dirty filters. Start with the bin.
Empty the bin immediately. Dirt must not be above the top mark. Pull the bin release catch upwards over a trash can. Close by pushing the cyclone down and the bin base up until it clicks.
Check for blockages. The motor will pulse if blocked. Disconnect from charger. Check: cyclones, wand attachment point, both ends of the wand, brush bar and air inlet on the cleaner head. Clear any obstructions.
Wash both filters. The Pre-filter lifts from the cyclone top. The Post-filter twists off anti-clockwise. Wash each under cold water until it runs clear. Dry for at least 24 hours. Must be completely dry before reinserting.
If that didn't work: The bin may not be sealed. After emptying, ensure the bin base is pushed fully upwards until it clicks shut. A poor seal kills suction.
Heads up: Using the machine with a full bin requires more frequent filter washing. Wash your filters every month for optimum performance.