Servo Motor Model PK266-01A Control Problem Having to do with torque

I'm having trouble with controlling a Servo Motor Model PK266-01A with a Arduino for a class project. All of the code and the circuit is working all together. However, the problem lies with there not having enough torque. Is there a way to increase the torque on this particular motor without damaging the arduino brain.

Motor info url:Item # PK266-01A, Stepper Motor On Oriental Motor USA

Please supply the SCHEMATIC as otherwise anyone is just guessing.

Power supply capacity and spec too !

What kind of motor control device are you using now?

Try connecting to external power source instead of using the 5V from arduino . Are powering up the arduino using USB or external power supply ?