...sounds and looks may like a servo torque inrush current limit issue. The sense of these kind of limiter is to protect the servo.
A high peak inrush current is always produced at the start of the servo motor/travel.
Are these servos programmable?
I´m using very much the Hitec D-servos line. The Hitec programming tool for these servos allows me to setup different protection (current) levels.
I agree with mhs try to duplicate this problem with a separate standalone servo tester.
May you could change the Champion SRS output voltage to the lowest level and run the test again.
See if you get a different result or not.