Door windows

[Tom Z]

My door windows have a guide fixed to the track, this guide has two screws and a plastic insert I'm thinking this is to be clamped to the glass and slide in the track ,am I on the wright track?

[jeffc280sl]

You are correct.  It's a very common problem for the guide jaws to separate from the window.  Do a search on "window jaws" and you will find advice on how to affix the jaw to the window.