Cordless vacuum makes a loud high-pitched whistling noise during use.

Safety first: Remove the battery before inspecting for cracks or reseating parts.

• Identify the noise source: Run the vacuum briefly and listen carefully to locate where the whistle is loudest (bin area, wand, floorhead). Then switch off and remove the battery.
• Check bin and cyclone seating: Ensure the dust bin is fully locked into place and the cyclone assembly is correctly seated. Reseat them firmly until they click.
• Inspect seals and gaskets: Look at the rubber seals around the bin lid, cyclone, and filter covers. Replace any that are torn or flattened.
• Check wand and joints: Inspect the metal/plastic wand and all joints for hairline cracks or gaps. Replace the wand if cracked.
• Test again: Reassemble and test. If the whistling persists but suction is normal, the noise is likely from a minor air leak and not harmful, but replacing the leaking component will reduce noise.