The jet is blocked more than likely.
To clean it with out expending masses of ink try the following.
You will need a refil syringe or small hypo syringe
or a small squeeze plastic bottle [ some cosmetics come in] thin plastic tube or drinking straw or cable sheath deionzed distilled water[Steam iron/battery stuff]alchohol[vodka] make a 10% solution pr window cleaning fluid[a water/alcohol solution]
The idea is to creatre a pump .
Remove the Cartridge. fit the tub/straw over the feed spike in the base of the chamber- and pump the fluid back and forth- This should blast the obtraction out.