How to prevent cogging

[PaulRotheram]

Never experienced this problem before. Im running micros for the winter and currently have an EZrun 18amp esc fitted, and have a 6800 motor ive imported which ran fine last week.
Unfortuantly i blew my esc last week by connecting it up wrong (less than a second of contact) ive now replaced it with like for like as it worked great.

Now im experiencing a slight cogging issue with the motor, it ran run fine for a moment, then the next when I try to put the power down, moving or when at half speed itl cog, then shoot off.

I have an EZrun 18t motor which ive fitted to see if it helps, and that motor works fine, very smooth, just not as much speed due to the wind difference.

Now is there anything I can do to get rid of the cogging with the other motor? i've inspected it and it is clean ( its only a meeting old ) free and nothing visually wrong.