I'm looking at refilling my carts for a canon 4300 since I had problems with ones that I transfered chips on and have since replaced with Canon carts. My question is, why can't you just inject the ink into the resivior through the air bleed hole on top of the cartridge. I see that most techniques require you to drill a new hole +/- plug the hole after refilling. What advantage is there to drilling a hole? Thanks in advance. Kevin