injector rebuild

Ok I've taken my injectors out because one of the ones rings was leaking but I've got other bits in the kit as shown hopefully in the picture now I think there filters should I change them and do the go in the top? If so how do I get them out? Same as what look like caps for the bottom, should I change and if so how

filters can be pulled out with self tapping screw & mole grips, tap new ones in gently with hard nylon or copper hammer ideally. assume others are bottom pintle caps which helps retain the lower o-ring, they can be pushed/tapped on .

Thanks it worked a treat