A good motor anyway. I do not know any details but I have heard of this before with less than perfect motors.
He may be talking about the little test to determine if the imbalance is caused by the utility voltage or something down stream of the utility such as cable, contactors, or even motor windings.
Suggestion: If it is a single phase motor, then the best way to resolve impedance imbalance is to use the electronic three phase to single phase converter, e.g. AC-DC-AC single phase. However, this appears to be a very rare solution. Normally, the three phase power supply is aligned with three phase motors that are normally balanced. Any imbalance is an irregular situation.
