The pump was overhauled as a part of routine maintenance ,there was no indication of vibration prior to overhauling.
LPT was carried out on impeller during overhauling and no damages where observed also when we calibrated the rotor for balancing we found that it was already under tolerance.
This are the main reasons I ruled out vane pass.
This horizontally mounted centrifugal pump acts as a overhung rotor,having a bellow in the suction side and connected to motor using a flexible coupling.Pump has 2 angle contact bearing in DE and one radial bearing in NDE.
I carried out shock pulse test and found bearing pulse to be just under warning range