steering box trouble
 

I have a 1990 full size blazer. I recently completely rebuilt my front end, except for the steering box, and still had a lot of slack. It turns out the bolts that hold it to the frame were loose allowing it to move around, but before I realized that was the problem I tightend the set screw on the top. Now the wheel doesn't return straight on it's own, even though I backed the set screw back out. Please help, thanks.