I am having small problems with channels going and coming when performing nozzle checks on my 9880. I have not much ink left in some of the carts, and I have seen there are air bubbles in the area close to the outlet of the carts. In some cases, these bubbles extend into the small thin pipe that links the bag to the outlet. Is it normal to have these bubbles? Should I prime out the carts until they disappear? Can these bubbles be the culprit to the intermittent disappearance of nozzles at the printed checks? What might be the origin of these bubbles? (low amount of ink, or disconnecting + shaking the carts improperly?).
Photo attached showing the problem, and also photo of the nozzle checks, with colours appearing and disappearing…