Hi, I don't know the answer to your question - but, why mess with refills when Cartridges for Epson are so cheap from click here I recently bought a pack of four for my Epson C86 for £11.49 (Incl vat and delivery)
As Technotiger says. Not worth the time/hassle refilling. The C66 is a chipped cartridge and will also need a "Chip Resetter" if you try to refill them. Easier, Quicker and Clean Hands if you buy from Choice Stationery. Follow Technotiger's link, the C66 is £11.49 for all four cartridges as well.