MKS777 servo jitters

mks777All bought new. These were all hv777 (not 777a+). I have stripped a pinion on one servo, stripped teeth on one, and sheared output sp onMKS Servo with Full Aluminum Case and Titanium Gears. The MKS HV Hh Voltage Servo series is desned to operate at hh voltage and low current, delivering hher torque per unit weht.