You need to machine two bearing blanks from billet with a precision bored hole for a piece of superior shafting or other ground round round bar stock. You simply insert the shaft and try to fit the bearing blanks into their bores, if one doesn't fit it's bent.
If you want to get real fancy you can machine a piece to fit into the center housing that accepts the shaft to ensure the center is aligned also. Putting 0.001" clearance on all the parts will allow everything to slide together if it's straight and also show you how bent the housing is.
Use a press to straighten the housing if it's warped, strategically placed weld beads work well also if you know what your doing.
“She may not look like much, but she's got it where it counts, kid. I've made a lot of special modifications myself.”
— Han Solo