Joint 6 is offset, how can it be put back to the original position?

When joint 6 is at Zero, it should be in the following position:

The range of the absolute encoder of joint 6 is ±420◦. Therefore, you must always rotate joint 6 within that range before deactivating the robot or shutting down the robot. Failure to do so may lead to an offset of ±120◦ in joint 6. 

To resolve this: 

1. Shut down the robot and disconnect your tooling.
2. Power up the robot, activate it and home it. 
3. Send the command "MoveJoints(0,0,0,0,0,720)".
4. Power down the robot. 
5. Reactivate it, home it and send the command "MoveJoints(0,0,0,0,0,0)". 
6. If J6 is still has an offset, Shut down the robot and Repeat steps 2-6 one more time.