259. When reviewing results of vibration analysis, vibration at a bearing occurs at the same frequency as the motor rpm, with a displacement in the radial direction that is twice that of the axial direction. Which of the following could this indicate?

Vibration at the motor's RPM with a radial displacement twice that of the axial direction indicates mechanical unbalance. This pattern, characterized by 1x running speed and predominantly radial vibration, is a classic signature of rotor unbalance at a bearing.