Is it 1) a red plastic switch, held in place by 2) a black rectangular (about 5mmx14mm) piece of plastic with two small holes in each end, through which 3) two white pins should have gone (one end attached to the back board, one end melted to secure the black plastic in place)?
No drawing nor picture just words I am afraid. I am not opening it up again if I don't have to: Every time some piece of plastic gets broken off.
Didn't happen to me. But I think you can fasten the black plastic any which way you like as long as it keeps the red switch in place.
While you're at it, why don't you give the loose red switch a paint job and make it better looking?