Brand new bearings have almost a notchy feel when simply pushed. When loaded, they typically smooth out.
If these are used, they cold have been subjected to just about anything. Is the bind felt shortly after changing direction or is it in the same spot everytime? If it's noticable at direction change, this is normal - it's the balls changing direction in the recirculation channels. If the bind is in the same spot each time or has a noticable pattern, it could be mechanical damage caused by impact.
I think in this case, you have to evaluate the cleanliness and determine whether the bind could be contamination also. Flush them out (if they are used) with a mild solvent - possibly pull the seals (be careful) and see whats behind them. Then purge with light oil while moving them to see if lubrication changes the feel.
Scott
Consistency is a good thing....unless you're consistently an idiot.