I took my Phantom 1 out of the case to fly it at the farm this weekend and did my normal startup procedures. Everything worked fine two days ago when I flew it last. Upon take off one of the motors didn't spin up to speed. I shut it down and tried again. Still the same problem. I pulled the battery out of the machine and turned the remote control off. I powered everything back up and still the same problem.

Here is exactly what the motor is doing. Upon power up 3 motors spin up normally and the 4th one does a jerky back and forth motion and doesn't speed up no mater what I do with the throttle or direction control. I also noticed that the green light underneath the motor that doens't work right also doesn't light up. I have a red light under 2 motors that are powering up properly and only 1 green light that is on under the motor that is working properly. Upon power down the motor that doesn't work properly blinks green for a split second.

Is this motor dead? What did I do wrong? I didn't crash and I didn't get the drone wet. It flew perfectly two days ago.

This is most probably a faulty ESC. The missing LED under that arm indicates this too. Sometimes electronic boards just get toasted.

Had similar problem.
Try pulling up on the offending motor, if it lifts, then circlip and collar have come off, and circlip probably stuck to motor rotor, stopping , or slowing the motor.

What is ESC?  How do you fix circling? I have three motors and corresponding running lights that won't run. Just jerk around.

Frosty Posted at 2015-3-27 08:26
What is ESC?  How do you fix circling? I have three motors and corresponding running lights that won ...

The ESC is the Electronic Speed Controller. This device takes the DC Voltage from the battery and converts it into three separate AC Voltages which are needed to turn the motor. These three voltages have separate phase values, separated by 120 Degrees, which when fed to the motor create a 360 degree rotation, or one complete revolution.

If one of the three outputs of the ESC fail, or one of the three windings inside the motor fail, then only two voltages will turn the motor causing it to jerk back and forth. The most common reason for this type of failure is if you have been using prop guards, taken them off, but used the same longer screws. These screws, because they are longer will screw into the motor housing and damage the internal windings causing a short which may also damage the ESC.

The Circlip is a small "C" shaped clip that fits around the shaft on the bottom of the motor to allow rotation without the motor completely separating.

Regards

Nidge