What causes this occurance and how can it be corrected?

Sammy,

How severe is the eccentricity? What type of equipment are you using to find this with?

I'm guessing a bad coil in either the rotor or stator, might be causing the rotor to shift in the stator, again guessing this is a babbit or sleeve type bearing with an oil film? This can also cause uneven or unexplainable wear patterns on those bearing surfaces in places where you wouldn't expect it, like on the upper half.

Would you be able to post your tester spectrum of this and give me more motor specs including the types of bearings?

One possible cause would be a high pole. If the DC poles have be removed for rewinding and not properly seated back on the rotor then you will have one or more high poles. The way to check for that is to measure the air gap at the same location to the stator iron, i.e. 12:00, for each pole. If a pole is found to be too high, then the pole should be removed and the mating surfaces checked and possibly machined to bring the pole back to an acceptable height.

Ronnie

Ronnie,

Right on! Anything to change the force in the air gap between the rotor and stator. Sometimes this can get bad enough to cause a rub.

Had the customer secure the motor and performed a voltage drop test on the rotor. Found a bad pole piece.
Thanks for the help