how do you fix the headlights in

Swmbo pointed out to me on Tuesday night, that the silver part below her NS headlight was loose, so had a look yesterday, it appears that this bit that may pop out on the top of the range model to wash the lights, but is fixed on her S model, is held in by springs, I had a fiddle with it but could not get it in right, anyone got the info on how to do this