The connection element of the Cappuccinatore (steam outlet nozzle) is dirty.
Pull the stainless steel cover off.
Pull the dispensing unit down to remove it.
Release the top part with the holder for the milk pipework from the dispensing spouts.
Clean all parts thoroughly.
Clean the surfaces of the central spout and the dispensing spouts with a damp cloth.
If the milk pipework connecting pieces are blocked, clean them under running water with the brush supplied:
Insert the brush into the pipe connecting piece.
Move it back and forth until all milk residue has been removed.