ink cartridges has never been successful because no-one has ever
explained how a cartridge works.
HOW A CARTRIDGE WORKS
An ink cartridge has a close-pore sponge filled with ink. The sponge is half-filled with ink for a normal cartridge and fully filled for a "long-run" cartridge.
This ink is worth about 10 cents.
That's why it is economical to refill a cartridge.
The sponge sits on a piece of filter paper with very fine pores and will not allow the ink to "drip through."
On the other side of the filter paper is a channel that feeds to the print-head. The print-head consists of lots of PIEZO PUMPS. These are micro diaphragms that bend when a voltage is applied to a sheet of insulating ceramic material.
Every time a voltage (and current) is applied to this micro pump, a dot of ink is ejected from the cartridge and lands on the paper below the cartridge.
When this dot of ink is released, and the pump returns to its normal position, ink from the channel flows into the piezo pump for the next "squirt."
The molecular attraction of water (ink is water) flows back through the channel and the ink under the filter draws more ink through the pores of the filter.
If you allow the cartridge to run out of ink, an air pocket is produced that eventually finds its way to the underside of the filter and as the ink in the channel is used, it would not have the "molecular-draw" to bring new ink through the filter.
If you simply fill a cartridge with ink, the channel below the filter will not be completely filled with ink and the cartridge will very soon stop printing.
WHAT TO DO
What you have to do is fill the channel with ink.
To do this, you need to fill the sponge with ink via a needle, through the hole in the top of the cartridge, then get the rubber squeezer from an eye dropper and fit it to the end of a 2.5cc syringe by drilling a hole in the top of the rubber squeezer and pushing it onto the syringe.
Now turn the cartridge up-side-down and place the squeezer over all the holes of the print-head and suck the air out of the squeezer by withdrawing the plunger of the syringe.
Keep doing this until ink appears on the print-head.
The channel is now filled with ink and an air-pocket will not be present.
You will now be able to use all the ink in the cartridge.