Yup...I missed that too
You did say the brushes were new
I shouldn't have assumed that you had seated the brushes, because i did.
I always clean the commentator when replacing brushes and use a seating stone.
What happens when you don't seat them there is a high possibility that a brush could jump off the surface breaking contact causing a drive error.
If you've ever heard clicking sound during run time that would be because the com bars have raised, generally caused from stalling the motor.
Anyways...

DOH!

Good deal though, glad you asked that mrfixit