VX - Power Window Clunk Noise When Opening

[chud]

Have a VX with power windows front and back. The front passenger window has made a clunk noise when going down for the past 6 months. The clunk noise occurs when the window is about 40 to 50 mm from the top of the door frame.

In the last week the driver's window has started making the same noise. It is one clunk, i.e. it's not a continuous noise as the window goes down. I haven't removed the the door trim yet (would like to avoid that if I can), any ideas on what could be the problem?

Could it have anything to do with the hex window height adjuster screw (which seems to be about the position when the clunk noise occurs)?

 

[goose202]

It'll be a broken plastic slider that moves in the slide on the bottom of the window.
About $4ea from Holden IIRC and a straight forward job to replace. Door trim has to be removed obviously to do it.