I had a problem with my Philips toothbrush: the sound got louder, the vibration effect got lost, and when I shook the toothbrush in my hand, I got aware that something was not right anymore inside.
So I opened it and found out it is just a little screw which had to be tightened again. I am sure Philips manufactured the device like this on purpose.
￼Photo 1 – To open the device you need some tools like these
2 – Press the housing together
3 – Be very careful when trying to pull the seal out. In my case, I broke it.
4 – Pull the seal off
6 – in my case, the engine was already coming out by itself after. Probably you will have to press against the shaft.
7 – pull it out
8 – Tighten this screw, use probably also loctide or another glue to keep it tight
9 – Bring it back inside
10 – If you before the housing like me, fix it with glue 😉