A vibration analysis on an electric motor shows significantradial vibrations at

A vibration analysis on an electric motor shows significantradial vibrations at 1x 2x 3x 4x the running speed of the motor.A particularly predominant peak shows near 12000 cpm. If the motorhas 4 rotor bars and runs at 2940rpm what would you suspect theproblem to be and how would you confirm your suspicions?