Well, then it could still be too tight or too loose- is it possible that you need another thin spacer in the stack? (Some stems are taller or shorter than others. If it's shorter than the stem that came off, it might need an extra spacer). Of you could have overtightened an mashed something. Or it may have nothing to do with the headset. Cleaning and greasing the frame where the bearings sit and where the fork and bearings contact couldn't hurt.