We ordered 2 and got them in on Wednesday. We saw yesterday that one of them felt like it locked up at one spot each rev, we spun it by hand first and caught this. We called AM, and Andy called us right back (!

). He recommended we put it in a vice, spin it with a drill for a few minutes to see if there was a burr that would clean up from the break in.
Note - we first pulled off the motor to ensure there was no visible problem like a loose piece of metal, broken tooth, etc.
We did as Andy suggested and it didn't really loosen up. We called back, and AM shipped replacement gears today for us to try out, hopefully that will fix it.
Moral of the story - nothing is perfect - but AM is a phenomenal company!