Servers by jDrones

One motor cogging

I have a quad with SunnySky X2820 motors. All motors seem to operate properly, yet one has a definite “cogging” when I turn the prop, while the other 3 do not. I disconnected all the ESCs and the cogging still remains on that one motor. I checked (and replaced) the bearings on that motor. It still cogs.
Why would one motor be different than the other 3, although all 4 seem to work perfectly?

Are the mounting screws too long and poking through to the windings?

No, I inspected them and looked for marks on the insulation (and shorted turns). All the windings have a resistance of close to 20 milliohms. Red-Yellow, Yellow-Black, Black-Yellow.

Servers by jDrones