Had a bad landing after which the motor has refused to rotate properly. I swapped electronics and verified that it's a motor issue. What would be the problem with this motor? How do i fix it ?

http://www.youtube.com/watch?v=1R0wPiLlEHs&feature=youtu.be

Ashu..remove the motor rotator, and check out the main shaft for any bend..and make sure the out runner case is not touching the stator set up..check, the all wires, coming from the motor, for any damage like cut outs or short circuit, as it crashes once.make sure all windings on poles are sound and not damaged in any way as burnt, or scared..make sure the free rotation in off condition, and check out all connectors for any loose contact, or dry solder..and try with an other ESC..once again..check out all connection for proper contact..as the tip connectors are in the heat srinking tube you must check it thouroughly..

 1) Open the can of the motor and see if some dust or Particles stuck to the magnets . Clean it and then try .  
2)  Also check the e-clips and Bearings.  
3)  If all those doesn't work check the Winding wires and soldreing ( Connecters ).

Yes,
The first process is open the motor and clean it.
If require, replace the shaft.

Please note that if your coil be damaged, or opened, it will burn insted of rotating (though badly). And of course, if the winding with multiple conductors, please cut odd the insulation sleeves to check joints.

Thanks

motor behaves such way when one of its wire not properly connected.i had same issue yesterday during quadcopter test and found that one wire wasn't connected properly.

I'll go with Dharmik here. I've had that problem a couple of times and it was always a bad connection between motor and ESC. Before opening the can please check motor-ESC wires. By the way, how are you connecting them? Bullet connectors?

And man, what are you doing with that motor in your hand? That's reckless. If you have to test a motor, always have it fixed to a non moving base and try not to have a prop attached. Even experienced people have ended up with stitches on their faces and hands while being careless with these things.

Happy Flying!

ashuthosh,
most likely there is a connection problem inside the motor winding. Check the continuity of the three leads coming out of the motor. On a multimeter betwen all three wires you should get continuity, <0.5 ohms, generally. If you find an open condition in any one, then there is an issue.

Thank you all for your replies. Like most of you suggested to have a look if there is any break in the motor winding, I just did that. As the motor got unmounted in flight, the wires got twisted and luckily one of them was broken in the heat shrink sleeve itself. Was easy enough to fix it. Didn't need to open it.

Will be doubly careful to verify all grub screw's are in place and secured with threadlock before mounting it.

I am careful with motor in hand giving up-throttle with a single click at a time till she rotates. Though risk was there chances were slim ...

http://www.youtube.com/watch?v=QfJzhbJoZ10&context=C386b05fADOEgsToPDskIj3yA0q_uMJE-u_pHiUGb0