Do not remove the cap, ever. Completely pointless, you are just creating work for yourself. Drip fill it through the ports (this will not contaminate the cartridge, EVER!!), when it starts to leak from the top ( it's just overfilled), turn it upright, leave it on a paper towel, which will force any excess ink out. If you're using decent inks these cartridges should always be perfect, if not its more than likely the print head.
Good luck.
Good luck.