Follow the instructions below:

1. Turn off the printer.


2. Press and hold the Feed/Pause Button and then turn on the printer.


3. For the Black Mark Sensor
   Release the button when the LED is lit in green (5 times) after the green/red LED blinks five times alternately.
   The LED color will change in the following order:
   Amber (lit) >  Red/Amber (blinks 5 times alternately) > Amber (5 times) > Green/Red (blinks 5 times alternately) > Green (5 times)  (Release the button here) > Red (5 times) > Green (lit)
   
   For the Gap Sensor
   Release the button when the LED is lit in red (5 times) after the green LED flashes five times.
   The LED color will change in the following order:
   Amber (lit) >  Red/Amber (blinks 5 times alternately) > Amber (5 times) > Green/Red (blinks 5 times alternately) > Green (5 times) > Red (5 times) (Release the button here) > Green (lit)
    

   You can also calibrate by using the BPM (Brother Printer Management Tool).