Hi, thank you for contacting JustAnswer.com. My name is Russell. I will do my best to provide the right answer to your question.
I'm not sure of the situation, since I don't (and you don't) have the first 'defective motor' to test and check.
It is remotely possible that the motor controller board is defective, and is mistakenly sensing the motor as defective. Or that the 'motor error' basically can apply to the motor controller board being defective also.
Do you use the machine for long continuous periods in a warm (84 degrees F or higher) environment, by chance?
If, also, any of the joints or axles in what the stride 1 motor drives is too stiff or seized-up, that might overstrain the motor to the point of failure.