Refilling a cartridge for a HP 970CXI printer may seem like a daunting task. However, it is actually very easy. There is even a tutorial video at tutorial video that walks through the process step by step.
The color cartridge is a little tricky. First, punch out the holes top holes and with the ink cartridge pointed toward you left to right fill them with yellow, magenta, and cyan. Fill the sprayer with the color ink that goes in each hole, insert the needle into the sponge insides that hole and add 10 to 12 milliliters of ink. After, the cartridge is full of ink just wipe it clean and put it in the printer.
The black cartridge works a little different. Find the ball bearing on the underside of the cartridge and push it into the cartridge. Inside the cartridge there is a bag that should have ink in it but has fallen in on itself as the ink emptied out of it so take a syringe full of air and use it to blow the bag back up through the hole. After the bag is open and full of air barely insert the needle into the bag and slowly add around 45 milliliters of ink. Now to reseal the hole take a bb, found in sporting goods department, and push it into the hole where the old ball bearing was. Now turn the cartridge over so that the bb is on the bottom and place it in a bowl. Over the course of 15 minutes around five milliliters of ink will drain out. Then it will stop draining and be ready to use. Simply clean it off and put it in the printer.