[Frank Miller]

As some said, it may need an alignment. With the steering linkage disconnected you should feel a slight drag as the wheel goes through the center. A rough adjustment for that, that gets you close is to center the steering wheel and loosen the four bolts that hold the sector housing. rotate that until it is loose and then bring it back until there is zero clearance.
When you say rebuilt, did you replace all the bearings worm and sector, or just put new gaskets in it? If your worm bearing preload is too tight it is possible to change those gaskets without removing the steering box. You'll have to loosen the column and then slide it up. Take out the four capscrews and add a gasket. Cut it so the sut is at the top where it will not see oil.