Hello, I have never seen shaft currents in a NEMA size motor but, If there are shaft currents present a complete circuit is needed. Does the bearing on the opposite end have electrical etching? Since this is a press fit it makes more sense that the electrical arcing would take place in the...
If you are experiencing bearing failures every two months my suggestion would be to remove the bearings in one month and have them analyzed by a bearing manufacturer. They should be well on their way to failing but not enough to destroy any evidence.
