Did you say it wasn't as smooth as the other ones if so it sounds to me like the rotor isn't centered properly. I had this with my motor, turns out the the end bell cap on the shaft side had not been tightend down correctly and was causing the rotor to touch the windings slightly, if I were you I would take the end bell cap off and tighten the screws down evenly and see if it makes a difference. I usually go to opposite corners tightening the screws down a little bit at a time.