You could send the pulse width to the serial port so you can inspect what is being sent to the servo.
Something like this would do the trick
void PulseServo(int channel,int pulsewidth)
{
// note that pulse variable is not needed and has been removed
int pin_num = 0;
pin_num = channel + 1;
if ((PulseWidth <= 2200) && (PulseWidth >= 600)) // 600 is a little low, try it with 800
{
digitalWrite(pin_num, HIGH);
delayMicroseconds(PulseWidth);
digitalWrite(pin_num, LOW);
}
else {
; you may want to add code here to blink a LED if Pulse WIdth is out of range
}
Serial.print("chan ");
Serial.print(Channel);
Serial.print("=");
Serial.print(PulseWidth);
Serial.print(", ");
}