I learned a little about unbalanced voltages.
Two transformer banks sit on adjacent poles. One is wye and the other is delta. The voltages on the consumer side of the wye transformers were 208, 208 and 200. On the delta bank they were 225, 238 and 252 (approximately as measured over a couple days).
A new, balanced, unloaded motor on the wye system drew 3.6 amps, 3.6 amps and 5.4 amps. On the delta system, the motor drew 7 amps, 8 amps and 2 amps. The rated flc of the motor was 6 amps.
It seems the high-line voltage difference created a larger voltage difference on the delta system than the wye system. When I think about it, now, it makes sense.
My customer was on the delta bank and had a motor blowing fuses.
I'm guessing that the counter emf (back emf) of the motor almost cancelled the applied forward voltage on one phase but didn't come near high enough to limit the current on the other two phases.
The last thing I learned is that it's way better if someone else pulls a motor on a Friday night and sends it away to be rewound over the weekend. Whew!
Oh, and one more thing. It's a prick trick to put a wrong panel cover on a panel so that only two of the six screws hold the cover and to glue the last 4 screws in place so they just look like they are holding. I took out the middle two screws first and the cover slipped down and dragged the breakers out of the panel.