DIAGNOSIS That’s an air leak. Something isn’t sealed properly, so air is being forced through a tiny gap, creating that whistle. It’s not the motor failing.
FIX Check all the connections. 1) Make sure the clear bin is clicked securely onto the main body. Take it off and reseat it firmly. 2) Check that the wand is fully pushed into both the vacuum body and the cleaner head—you should hear a definite ‘click.’ 3) Inspect the seals (the little rubber gaskets) on the wand ends and where the bin attaches. Are they cracked, missing, or have debris on them? Wipe them clean.
IF THAT DIDN’T WORK The noise might be coming from the cleaner head itself. Detach it and run the vacuum. If the whistle stops, the leak is at the head. Check the seal on the cleaner head neck and make sure the brush bar is correctly installed and not rubbing.
HEADS UP That whistle means you’re losing suction power. Running it like this for a long time can also let fine dust into places it shouldn’t be, so it’s worth tracking down. Avoid using third-party accessories or bins that don’t fit the original seals perfectly.