I have a custom build quadcopter with Pixhawk FC along with 980kv SunnySky motors and ReadytoSky 60A opto ESCs. One particular motor shutdowns abruptly in a flight or sometimes doesn't spins on arming .
I swapped the motors and the pixhawk connections too but the problem persisted on a particular side(right rear hand) of the quadcopter, so my Pixhawk and motor seems fine. I guess the problem is with that particular ESC.

My main query is whether the ESCs problem could be fixed or should I replace it with a new one.
And yes my connections are all solid for I checked them properly.

Any help or suggestion is much appreciated.

Thanks in advance

As you are using 950 Kv motors, i hope u are using 1050 or 9450 propellers, for these combination 30A persistent current ESC is recommended, with peak current of 40A (for 10 sec). But, you are using 60A ECS, that i think is creating problem. try changing youre ESC with 30A one.