What is motor restacking, and when does it apply?
Restacking replaces the steel laminations inside a motor’s stator when core iron testing shows the iron itself has failed. A standard rewind won’t solve the problem if the core is too far gone, because the motor won’t meet efficiency requirements no matter how well it’s rewound.
Restacking typically makes economic sense for motors above 600 horsepower, where replacement costs are high enough that rebuilding the core pays off. Below that threshold, replacement usually wins.