Rattle Issue - Motors not in sync?

[coudron]

I just got my EleksDraw up and running, but if it moves with any speed, there's a terrible rattle sound. It's almost as if it's trying to do micro steps between the motors vs moving both motors at once?

Here's a link to a video of it rattling as it moves:
https://www.dropbox.com/s/fel9ozhujayjnmf/Video Nov 08%2C 10 31 33 PM.mov?dl=0

Any help fixing this would be appreciated.