Improper maintenance can lead to a multitude of symptoms and error codes. Error 1000 means the left side brush is not spinning. Please make sure it is clean and clear of debris.

B = left
Note: The brushes are not interchangeable, but mirror images of each other. They will only function properly if installed correctly. They are colored and labeled differently to help the user install them.
Visit, “Edge Sweeping Brush Care, All Roomba Models.” for more detail.
A reboot may also help clear the error. Reboot the robot by removing it from the dock and holding down the power button on the robot for 10 seconds. Hold the button again for 3 seconds to turn it back on. Doing so should clear the error from the robot's memory.
If the side brush is clean and still not spinning, please contact iRobot Customer Care.
For expedited service, please have the following ready: