Front brake caliper will not seperate! Aragh!

[susho]

So what is the preferred method to separate the long backside arm from the main caliper? I can turn it out of the way to access the pads etc but it has no lateral movement on it's pin and so only the bottom half of the brake actuates while the top is rock solid and will not push out onto the rotor when braking. I want to remove the swing arm part and see what is causing the stiffness there.
I have beat on it with a hammer already so forget that and I can find no cir-clip or other devise that holds anything in place there under the boot.
WTF?