uPVC window latch mechanism rattle

[dormermike]

Does anyone know why latch mechanisms inside the sash would rattle under normal use, e.g. opening a window and it rattles, give the sash a little thump and it rattles. When it's closed/engaged it's silent.

Is there a way to adjust it out?

I asked the installer and he unfortunately went from hero to zero claiming "all do that" and then "I'd need to see what the manufacturer says because I've never had a complaint about it before. Right.

Thanks
Mike