Je n’ai pas tenté le flush ni le re-fill, surtout que le re-fill ne peut pas être fait sur un seul channel il me semble donc gaspillage important 
Bon courage à toi, n’hésite pas à me dire si ça a fonctionné 
Merci ! je te tiens au courant.
The most important thing to do is identify the exact channel that has settled pigment (aka, Cyan or Light Cyan channels) by printing the channel separator image from QTR in Calibration mode:
VPI-10InkSep.tif.zip (674.1 KB)
Then make sure you have a good cartridge (agitated ink, even do a sample brush on some paper to verify color) then print 2x of 24"x90" or 2x of 44"x90" on some cheap canon bond paper of just that channel using a flush image in calibration mode (720 or 1440 BiD fastest printing)
QTR_Flush_Images.zip (87.8 KB)
This will clear the channel (about 40mL of ink on a 9900 or 30mL of ink on the 7900) without using any other channel.
best,
Walker