This has been one of the greatest yet super on the down low hack. Costco wants you to buy those new cartridges so you have to know they do it to get it done. Ain't no big signs at my Costco announcing this service.
Reset ink cartridge memory to get as much ink as possible. Find the circuit board on your cartridge. Often its brown or green in color with black, white, or gold circuits. Just above the circuit board you will see a small hole. Press a paper clip inside the hole (see image below) and the memory on your cartridge should be reset. Put the cartridge back in your printer and your ink level monitor should now give you a more accurate reading.