Dear RC4, once the caliper is out of the bike, you must open it, unscrewing the two screws blocking the two parts.You will find a little hole connecting the two parts. Blow air in these holes, and close with your finger the oil inner (only on one side...). Once the pistons are out, check theme, and the seals. If they are not damage, you do not need to replace theme. I hope you could understand me... sorry for my English... Have a nice day.
Massimo