djdigy wrote: i wonder if the burrs are attached to the motor so they are also subject to change when the motor is replaced?
Yes, they are. The dc motor, gearbox, and ring burr are replaced as a single unit. You now have a new ring burr and your original cone burr which in part explains the change in grind shim and setting.
My 270W motor was replaced by Baratza due to a broken commutator at about 5 or so months. As I live in Seattle I just drove the grinder over to the Baratza office and they fixed it on the spot as I watched. They mentioned there was a manufacturing flaw with the dc motor commutator/armature windings region which can cause dead spots in the motor. If the motor stops rotating at a dead spot, it will not grind. If you turn the ring burr a little out of the 'dead zone' you can make the motor work again... until you stop on the dead spot again. Think of it like Russian roulette. I believe this is what others have found, which can be confusing to diagnose: One day grinder counts down/lights up but the motor doesn't turn; user tries various troubleshooting including removing the lower burr, thereby rotating the motor out of the dead spot; grinder works again until it stops in a dead zone.