Use:
rinsed well the cartridge several times to remove a maximum of hair, although the water is emptied through the small opening in it (even using a small syringe if you have it available) then filling the cartridge by putting the liquid in the 'greater openness, perso I filled 3/4 and then you put the cartridge in the service station and is normally used.
Note: when I handed the cartridge once filled, the station still displayed me the icon that indicates that the cartridge is empty few seconds that has disappeared once started cleaning.
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