Dear "przytek";
Sorry to hear your problems with Dualsky motors, it is surprising.
I am using Dualsky motor for F3A since 5 years ago. My first Dualsky XM6360CA was replaced after 200 flights because new and lighter XM6355DA became available. XM6355DA is now more than 500 flights and not problem at all, even not replace ball bearings. Some times I open my plane motor cover to look at, and all is Ok in the motor.
It is difficult that magnets came out of position in Dualsky motor, as they are supported in the can and glue is good. In Spain summer we have more than 34º and in extremately hot days I mesure close to 60ª in the motor can some seconds after landing and not problem at all. I think, because the strange sound it is possible you do not have the right speed controller setting and it give you the problems and overheating. For sure if you include new message with the propeller, speed controller brand and the settings someone can help you to solve the problem. Also you can contact directly to Dualsky.
Last July we had the Spanish championship and we are 5 pilots from 21 with Dualsky, and all of us very satisfied. It included Juan Rombaut and his father, supported by Dualsky. I was supported by the company I worked, but I finish with this company one and half year ago and I still using Dualsky motors. Other two pilots do not have any support and I am sure they are over 500 flights on Dualsky without troubles.
Because my work at radio control companies I can tell you Dualsky motors are the best in China.