Following this topic:

http://singletrackworld.com/forum/topic/leaking-pistions-hope-caliper-which-model-and-how-to-please

I have the correct seal kit, the bore tool has worked fine, outer pistion pushed out but how on earth do you get the inner piston out??

And the edges of the pistons look a little chipped so I guess these will need replacing too?

Can’t remember if it was a hope or not but I’ve used an air compressor to pop them out before, and co2 tyre inflator to do the same job.

I’ve had a good enough seal with track pump on the bleed nipple

Cheers guys, track pump and a load of faffing with washers did it.

I realise yours were already off the bike minus the hoses but next time remove the inner piston first whilst lever, hose and fluid are still in place.
Hold the outer piston in whilst pumping the brake lever until the inner one drops out; the outer one may fall out of its own accord or can be accessed by removing the bore cap.

if you have the kit and all the stuff you’re most of the way there; Hope do a very good service in future if you need it — got my old Mini brake serviced that way..

Bit late but for future reference: Instructions for mine was to hold the outer piston in it’s bore then put a pump on the bleed nipple (with it open). One pump and the piston pops out then remove the other via wiggling it or removing the bore cap.