After I manually have the level indicator back, I could now take advantage of the full scope of the toner.
Reset functions as follows:
1. Switch off the power switch
2. Open the door and keep the key-press Go / Start and then on while holding down the GO / Start button power switch
3. If all the LEDs light release GO / Start button
4. After LEDs have gone 2x GO / Start button press
5. 1-2 sec. Pause
6. Press 6x GO / Start button
7. Close the flap