Dean, did you feel any rough or sloppy movement in the ball joints? They'd be shot for sure if you did as good ball joints don't move by hand well at all. I couldn't hazard a guess about turning the leaf. I will say this: clamp the spring in the center to a level beam (sq. tube, small I-beam, etc) above the floor and measure the distance from each end to the floor. It's a quick down and dirty test to see if the leaf is more compressed on one side. It won't tell you if one side is weaker though. A shop could do a weight deflection test for you. Just my 2c's.
