Zanussi FL881 door problem?

I have a Zanussi Fl881 and the door catch is not allowing the machine to cycle. Some times it starts after a few sharp slaps on the door. I can take the door catch out easily enough but can it be repaired or is replacement the only answer? The mechanics of it seem quite simple.Also can anyone tell me ,it has 3 lead going to the switch 2 white and 1 orange which one is the " in".Please advise as I'm to hard up to fork out the 30 odd quid for a new catch !