I fitted a CIS system, following the instructions exactly. The magenta cartridge leaked from the air vent hole beneath the ink feed hole. The supplier sent me a new cartridge. I fitted it and it still leaks. If I fit knotted feed tubes, it doesn't leak. If I fit standard cartridges, it doesn't leak. I moved the reservoir, so it was below the desk on which the printer sits and it still leaks. None of the other cartridges leak.
Can anyone help, please?