Good results this week with re-inking of the colour cartridges of my Canon iP5200 printer. I have been using this printer for black-and-white work and I let the colour run out months ago. I expected that the old ink would have blocked the heads forever so it was a pleasant surprise to get colour printing working again. After the refill I needed to run cleaning 5 times before getting a reasonable test result. It has since got better with repeated use until now it is doing a useful job of printing photos. The "JET TEC" kit I bought had good instructions and a syringe. I have since discovered bulk ink suppliers online and I am trying some of that ink. This printer has 3rd party imitation cartridges and I discovered they had refilling holes with plastic plugs so refilling was remarkably easy. Important to cover the exit hole with tape and work on newspaper and wear latex gloves because these CLI-8 cartridges do leak a little on removing the exit hole tape after filling and replacing the plug.
I have also tried refilling another printer, Brother DC-110 with LC47 cartridges. That worked and is my easiest refill so far because the cartridge has a valve that closes on removal so preventing leaks.
I am also successful with 1 trial with an HP 56 black cartridge.
My earlier unsuccessful adventures many years ago were very messy with most of the ink going everywhere except inside the cartridge. This was with a Canon BC-02 cartridge which was a lot more difficult than this week's experiments.