Factory setting for 'brightness' on Apple Cinema LED 24" ??

I have just bought Spyder3 Pro to calibrate my new 24" cinema LCD monitor. Prior to this I had tried to use the unbuilt calibration system. I also played about with the 'brightness' (backlight) slider. On installation, Spyder asks you to reset the backlight setting to it's original position. I have NO idea what this was! Does anyone know how to reset the monitor to factory defaults? Obviously this has an effect on my calibration! Thanks for any help. Sorry if it's a dumb question... I'm new to Macs...