Hello Keith and meepmeepmayer and thanks for your anwser.
I'm not sure my english is really good to explain my issue but I'll try to do my best.
I have an issue and I should had told it before like on the top of the topic. I apologize.
First of all, since I bought my EUC, there's a position of the wheel that when I turn it on, the wheel vibrate abnormally when I ride it.
In this situation, I notice that turning off my wheel, rotate the wheel of a few cm and turn it back on fix the issue until I turn it on again on this position. Not a big deal.
But few months ago, I started to realize that my EUC had a strange behavior :
When I leaned forward a little too much, the tilt back wasn't smooth as it was back in the time : It was giving little hits.
Beside of that, I do a kind of bump jump with 5 cm high objects : you lead over it and you jump as soon as you feel that the wheel is going to hit it. It makes you bounce high and I love the feeling.
Recently after making a big bump jump, the wheel made a strange electronic noise for a few seconds then became silent again. I went back on it and the driving was again fluid as in the first days: no more strange reaction when I lean forward too much.
On the other hand, since, it start vibrate abnormally around 20 km/h and trying the fix by turning the wheel of few cm and turning on again doesn't do anything.
Something telling me that my issue isn't coming from the bearings but is more something liked with stator/rotor.
The vibration feeling is exactly the same as the issue I had when I start my wheel in a wrong position.