I can hear it clicking but I'm beginning to think it may be defective. Any Ideas?
Mine click, and they work fine. I don't think clicking is a good sign of a defective unit.
NewPing sonar[SONAR_NUM] = { // Sensor object array.
NewPing(5, 3, MAX_DISTANCE), // Each sensor's trigger pin, echo pin, and max distance to ping.};
You don't need to set up an array with only one sensor, that may be causing some issues.
I would recommend copying the simplest example in the NewPing files and using that to verify that you can read from the sensor. Then start to add complexity such as making the sketch time-driven.