I didn't flush anything and all has worked well for a cartridge or two, but I'm seeing the yellow ink is translucent in the refill bottle but coagulated (there's a precipitate visible) in the cartridge after filling!
What to do?
Can I flush the cartridge with an alcohol/water solvent...
New Canon MX870, Image Specialist inks from ebay, Octoink Sqeasy fill... so far looking great.
First fill and ... no yellow at all. Everything else fine. Deep clean, clean, 5 nozzle checks. Not a spot of yellow.
So,... I refilled empty (nothing more, like a purge) cartridges. Perhaps I mixed...