Sometimes they are tighter than you'd like them to be. I've gotten them out by pushing in whatever direction they seem to want to move, which helps free them up. Then going back and forth until they slide out. Lubing everything up for install makes them slide in easier. The center pin holds the spiders in place. If the the carrier is turned any while the center pin is out, the spiders could have shifted slightly and made it harder to install the pin.
How bad was the axle shaft bent? I have seen them with a bent flange but otherwise fine. I would think you'd have to hit pretty hard to damage the carrier/center pin. If its really that hard to get the pin in, I would check to make sure the pin is straight, etc and go from there.
