Having a quick look at rear brakes just now - pins are moving very freely a couple of mm , so they are not corroded in, but they don't seem to wan to move any further?
Do they just hammer out, or am I missing some retaining spring/clip?
the pins are held in by a metal barrel spring which can bond itself to the aluminium caliper and takes a lot of force to move, i broke a punch and ended up drilling it out, if your doing the job buy replacement pins as well.
They can be a bugger to get out, you WILL need a proper set of pin punches, they are bad enough to get out when calipers are on a workshop bench let alone when on a car, so expect an harder job when on the car, the higher the miles the harder the job.