elixer pistons

The Cookie Monster

i have some avid elixers which have done a lot of getting dusty or muddy and a lot of sitting in a bike shed. they need some bleeding and i CANNOT get the pistons back in, i have taken out the pads, drained all the fluid and split the caliper, put the body in a rawhide vice and pressed on the piston using a 10mm ring spanner (seemed to fit the best) and still, it wouldn't budge. it moves when it has fluid and i pull the lever, it just wont depress flush with the caliper body.

any ideas? is it meant to stick out a little? do i need to pull the piston out and look at the seal? if so, how careful do i need to be of scratching the piston body? what i would give for some nice simple rod brakes...

Thanks