Coolant pump replacement! But pump is stuck?
 

I've taken off all the back screws, the thermostat coolant pipe and housing is out of the way, I can see the wheel and all the screws are off but the coolant pump will not move. It makes no sense, I have removed upper and lower bolts, fitted the water pump holding tool and removed the 3 pinion bolts. Nothing appears to be in the way. I have tried giving it a little nudge with a small pry bar even! What might I be missing?