It was in august 2023, when I drove the motor too hot... and the "zing-zing" sound once appeared.
The stator inside the motor can easily reach about 120°C or even more (at high current over a long period), so the diameter of the stator (nickel steel alloy assumed) extends about 0.5mm (compared to 20°C). That's enough to touch prone magnets.... If I had tried to remove the magnets you've spotted, I would have had to use brute force (because they are firmly glued and not loose), and the magnets would not have survived.
And by the way: no need to worry, I already have a spare motor inside my garage.... just in case.
