51 16 ... Replacing button for armrest in center console

Insert feeler gauge (1) between pushbutton (2) and housing (3).

Fig 1: Inserting Feeler Gauge Between Pushbutton And Housing

Courtesy of BMW OF NORTH AMERICA, INC.

Press feeler gauge (1) downwards until pushbutton (2) snaps out upwards slightly.

Remove feeler gauge (1).

Lever out pushbutton (2) sideways and remove from housing (3).

Fig 2: Removing Pushbutton Using Feeler Gauge

Courtesy of BMW OF NORTH AMERICA, INC.

Installation: 

Pushbutton (1) must not be damaged.

If necessary, vacuum out duct (2).

Fig 3: Locating Vacuum Out Duct

Courtesy of BMW OF NORTH AMERICA, INC.