First, the motor made a strange metallic clicking noise when I turned it with my hand. After that, I made 2 short <5 min flights, and in the second one I accidentally crashed into a branch of a tree and the drone fell on the props onto the ground. There was no damage except one broken prop. After these flights, I tried to shake the noisy motor and the sound disappeared. But then I noticed that that motor works much louder than the others like described here: DJI Phantom 3 (Standard) Motor Noise?. I must say that I am not sure that this loudness didn't take place before. Do I have to replace the motor? Is there any danger flying with it? Can I just disassemble the motor and clean inside of it?