Weird and loud buzzing from electric window

[phn]

Hi there, when the passengers side window of my Chimaera is operated sometimes there follows some pretty loud buzzing noises from the door that continue intermittantly even after the switch is released. The window still operates though, and if you keep moving the window up / down for a while this seems to stop the random buzzing noises.

Did anyone ever experience this before or have any ideas what could be casuing this?

Many thanks, Philip.