Power off the machine. On the rear wall, unscrew the three screws of the motor panel:
Remove the terminals from the doser motors. If you are replacing the motors completely, it is enough to detach the mounting plate.
To remove a motor from the plate, hold the lock nut with pliers and unscrew the two screws securing the gearbox:
Reassemble the unit in reverse order. Pay attention to the 
terminal connection 
turns clockwise