IF the blade axle is bent the blades would not stay in track. You could track them and have them in track , but soon as you pumped the collective couple of times they would be out of track again .
They would be continously going in and out of track if the blade axle is bent.
How did you determine the replacement axle was bent?
Also usually a bent blade axle does not cause the vibration your describing except when the blades are out of track.

Just trying to help.

David