From what I understand SEM DC servo motors are robust and built very well. I tested a motor with DC power (in the appropriate voltage range), then shipped the motor with the shaft protected from damage, packaged properly, etc. Now the buyer claims the motor will not spin free, but the box wasn't overly banged up by USPS, no disaster just typical stuff. What could cause the motor to stop free spinning by hand. The motor is an MT30M4-59 SEM motor.