Vacuum makes a high-pitched whistling noise during use.

Safety first: Remove the battery before inspection.

• Check dust cup fit: Remove and reinstall the dust cup, ensuring it clicks firmly into place. Inspect the latch for damage.
• Inspect for cracks: Examine the dust cup and cyclone assembly for hairline cracks or holes. Replace if any are found.
• Examine seals: Look at the rubber gasket around the filter and dust cup interface. Clean off dust and ensure it is seated evenly. Replace if torn or flattened.
• Check connections: Ensure the extension pipe and accessories are fully inserted and locked. Loose joints can cause whistling and suction loss.