My boot won't open as the button isn't hitting the mechanism.

I've had a quick look inside and it looks as if the white plastic piece attached to the button has rotated away from the position it should be in which is why it's not catching.
I've moved it back, but is there any way of tightening it so it doesn't rotate again? Apart from a stupid washer doing the grand sum of naff all, I can't see a way?