well for one thing when people think they have a bad stepper motor 99.9999% of the time it's either a bad wire or a dodgy stepper driver.
Stepper motors are like cockroaches - come armageddon roaches will be riding around on solar powered vehicles driven by stepper motors.

Check your wiring and stepper motor drivers.

Most motors are interchangeable.
If you bought another motor and it's not working - then that's a pretty good indication that it's a wiring or stepper driver issue.