How to dismantle Citroen Picasso headlight switch?

Xsara Picasso 2004. Headlights flashing randomly, central locking unreliable. Problem seems to be caused by fault in lights switch transmitting stray signals via Comm 200 unit. Temporary fix is a rubber band to hold switch button in a certain alignment to the stalk. I would like to take the switch apart for cleaning. Is this possible without demounting the whole unit? Thanks for any help.