-Unlock the locking device by turning it 60° anticlockwise according to the indication mark (1).The red mark should be visible.-Feed the vapour tube (2) in until it stops.-Then, lock the locking device by turning it clockwise by 60°.-Push the lock knob to the end position. The red mark should be covered and invisible.-The vapour tube is not allowed to be pulled out!-Check the correct axial locking device on the vapour tube.-Keep the red mark invisible.