How do I connect the masher / puree accessory to the hand blender?

First, fit the gearbox to the shaft by turning in a clockwise direction until it locks into place. Turn the puree accessory upside down and fit the paddle over the central hub and turn counter-clockwise to locate (If the gearbox is not fitted properly, then the paddle will not secure in place). Align the assembled puree accessory with the motor body and push the pieces together until they click.
After use, unplug the appliance. Remove the paddle by turning clockwise. Then, press the release buttons to detach the puree accessory from the motor part. Separate the gearbox from the shaft by turning counter-clockwise.