I chatted directly with Philips Customer Service and they said that the brush cannot be ordered separately. You have to replace the whole handle. I was given an incorrect article number and two links to spare parts dealers in Germany, despite being told that I live in Switzerland. After a short search, I came across this:
https://www.migros-service.ch/de... I only need the plastic ring with the blue bristles, but it doesn't seem to be available separately. Hope this helps.
