Faulty Hobbywing XRotor 40A-OPTO ESC

One of my Hobbywing XRotor 40A-OPTO ESC is faulty, its not rotating motor at same speed of other motors with same throttle input?
I checked with different motor, so I confirm that it’s not motor issue.How can I repair it?
Please visit video, see circled motor is rotating slower than other motors.

You are saying that the ESC is faulty so I guess you should replace it.

Any chance to repair it? Also when I raise throttle then it starts rotating fast.

DId you calibrate the ESCs?
As far as repair I have no idea, but it seems unlikely.

Yes, i calibrated 1by1 as well as one at a time from Pixhawk.
That faulty ESC works fine when throttle goes higher than 50% i mean for high throat value it works.