I have owned the Phantom 3 Professional for around one month now, and recently, I have encountered problems when attempting to take off. When I take off, only 3 motors spin, preventing the drone from going into the air. There is no visual difference betweeen the four motors on my drone, and each has the same resistance to being turned by hand. I have not crashed the drone and there is nothing else that I can think of that could affect the motors. I also tried removing the shock absorbes to see if any cables were unplugged, and they were all connected properly.

Does anyone have suggestions or methods for fixing this problem? I would be glad to try methods and respond to people.

possible that there is some type of dirt  or debris that got caught in one of the motors other than that I would recommend getting hold of DJ and tell them your issue

Yea check it for dirt and check that motor turns as free as the others, its likely a faulty ESC and needs to go into DJI sorry

Hate to say it. But a service from DJI May be in order.
Hopefully you can find a fix, or say bye bye birdie, for 6-8 long weeks.

If you have some compressed air, try and give that motor a few blasts. . .
See if you can't dislodge some debris or other obstruction. Hold it upside down and spray, while gently turning the motor shaft.

Hopeful you can correct the issue.

RedHotPoker

He already said it turns just as easily as the other three.