I have the same issue with mine. Also the rotors do not come off easily like you state in videos. Well the rotor comes off easily enough but the black retainer pieces remain stuck on the shaft and are practical impossible to remove. I had to force them off with tools with way to much force and risk snapping the shaft. If you can include some more detail on the videos or instructions since there is no mention of these parts in the manual or video and they both assume this peice comes off with the rotor which it most certainly does not.
I had the same issue and the longer shaft on the one side was causing the rotor to hit the cage when it was spinning causing a very loud noise and vibration. the only way I was able to get rid or this problem was to use a a rotor with a B cage. Which of coarse resulted in very poor flow from that side in either direction. But at least it is quiet and will not damage itself until I someone can come up with a proper solution. This problem was out of the box. Seems like a quality control problem. Is the motor rotor put in backwards? should it be longer if so on what side. and how do you get those black peaces onto the motor shaft without extreme force and same for removing them. Also what are the differences in the black or the other clear/white bushings (Black pieces on the shaft in the first picture shown in the thread) that where supplied. The manual is clearly to vague.