Vacuum runs but makes a loud high-pitched whistling noise during operation.

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

• 1. Localize the sound: Run the vacuum briefly and listen carefully to identify where the whistling is loudest (bin area, filter cover, wand connection).
• 2. Inspect bin and cyclone: Remove the bin and check for hairline cracks or warped plastic. Replace the bin if cracked.
• 3. Check seals: Examine all rubber seals around the bin, filter cover, and HEPA filter. Replace any that are hardened, torn, or compressed.
• 4. Verify proper assembly: Ensure the HEPA filter is fully seated and the cover is latched securely. Misalignment can create small gaps that whistle.
• 5. Test connections: Check that the wand and nozzle click firmly into place. Worn locking tabs can cause leaks; replace the affected component if loose.

Air leaks reduce suction efficiency; replacing worn seals and cracked housings restores performance and reduces noise.