reassemble steam delivering button on tefal steam generator?

my tefal steam generator pro iron fell on the floor.
the top flap of the handle has come off ,nothing is broken .the steam generating button has a plastic cup
which can be easily put in its place with the electric wire connector above it . But after assembly there is no 'spring' in the button so there is no steam generation. How can I assemble the button so that pressing it will generate the steam. Please help thanks