Water Pump Shaft Removal

[Will N]

Ok, so I'm rebuilding a water pump. I've unscrewed the packing nut, and I am trying to remove the shaft from the housing. It won't budge. (There isn't that collar at the front of the shaft to prevent fore/aft play.) The shaft spins freely in the bearings. I have it in a press but I don't want to put too much pressure on it fearing I'll crack the housing. I kroiled and heated but it won't budge. What am I missing?