Bearing Replacement in 76 KZ750

I'm rebuilding the starter in my 75 KZ750(B1) - everything is going fine except I needed to replace the bearing on the output shaft. I can press the bearing into the housing, but I can't press the output shaft into it - it just pops the bearing out. How can I press these two together? I wanted to just leave the old one it, but it was 'scratchy' in one place. Any help would be great - this is my last step!