Servos constantly moving forwards, even when stopped

My servos on a skid-steer robot are commanded at 1740 when armed, even though they have a range of 1000-2000 with a trim at 1500. Servo 1 is set to function 74 (throttle right), and 3 is set to 73 (throttle left). Holding the joystick in the center commands the motors at 1740. Holding the throttle fully up is 2000, and fully down in 1500. Going to a bottom corner commands one motor at 1000 and the other at 2000. When disarmed, they are (correctly) held at 1500. This is an Aion Robotics R1, running ArduRover 3.5.1. Here is a log file.

@lights0123, it looks like something may have gone wrong during the RC (input calibration) and RC3_TRIM (the input trim) has been set to 999 instead of 1500. I suspect what happened is the throttle was held low during the last stage of the calibration.