Need help- ESC calibration

Good morning, I am building a quadcopter using navio+ and raspberry pi, I am also using APM mission planner to control it. I am using wi-fi signals. Every thing was fine and was working correctly but suddenly two of the motors stop spinning with low throttle values. They start spinning only with high throttle values: one of them when the throttle is above 50% and the other when it is above 60%. I tried ESCs calibration from mission planner (all at one) but no result. I can not do the manual calibration since I do not have radio receiver. What is the solution? is there is any possible other solution for the problem other than ESCs calibration ?

Hi! There are a couple of threads here where Navio users have successfuly calibrated ESCs without a transmitter:

You can try to do this using MAVProxy.