Vacuum makes a high-pitched whistling noise during use

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

• Localize the sound: Run the vacuum briefly (with battery installed) and move your hand around joints and seams to feel for escaping air. Then remove the battery before proceeding.
• Inspect bin and body: Look for hairline cracks in the dust container and around the bin latch area. Replace the bin if cracked.
• Check seals and O-rings: Examine rubber seals at the bin outlet, filter cover, and tube connection. If they are flattened, torn, or missing, replace them with Bosch seals.
• Secure covers: Ensure the filter cover and bin are fully latched. Slight misalignment can cause whistling and suction loss.
• Temporary test: As a diagnostic step only, gently press on suspected leak areas while running the vacuum. If the noise stops, that area needs sealing or part replacement.