Connect an open ended hose/adaptor to the red banded service line and place it in a suitable waste oil container.
From the start up menu touch the gear icon at the bottom of the screen.
Locate and press the scale button.
Locate the T1&T2 buttons at the bottom of the screen they should be grey, and when you touch them they will turn green. When they are green, this puts the machine into calibration mode.
Touch the home button on the lower left side of the screen to get back to the main menu.
Now empty each tank one at a time, you will notice the pump continues to run even after the tank is empty. Let the pump run until the machine shuts itself off.
Repeat the procedure on the opposite tank.
Touch the gear at the bottom of the screen, press the scale button and look at the tank sensors. Both tanks should be -0.6 and both tanks should be empty.
Note: if you have a PXT 1401 series machine and the scales are out of calibration update the software before attempting to calibrate the scales.