Philips Sonicare Toothbrush How Do You Clean The Gunk From An Electric Toothbrush?

How do you clean the gunk from an electric toothbrush? - philips sonicare toothbrush

I hope you can help me here, because the manufacturer Philips (Sonicare) did not even answer this question correctly. Almost every week collecting nasty dark film in the head of the electric toothbrush. First, is that normal? Someone else has this problem? I have to scrub a manual toothbrush to the film. Is this a widespread phenomenon of the electric toothbrush because I'm too big to ignore this film and only the head change every 3-4 months? It is always a nuisance to clean this movie every week!