Sticking window stays

What about trying WD40? But I would have thought silicon spray should have worked.

Are you perhaps confusing sticking with the need to fully open the window to release the latching mechanism in the stays?

Forcing the window to close will probably break the stays eventually. Nearly all stays are made in this way.

The Thetford silicone spray for the toilet seal works when the ones on our caravan stick. Those lock with screw knobs though, and will close from any position. The main problem one is that in the bathroom, possibly due to condensation.

 I'd  agree  with  SteveL  on  this.  The  Problem  with  WD40  is  that  the  original  caused  some  plastics  to  soften,  now  there  is a  version  with  Silicone  and  another  with  PTFE.  I  think  even  3 in 1  oil  has  similar  versions  as  well.

Do you have Seitz windows? If so, they are designed to allow closure after being opened to their full extent.

As TW has pointed out, above

Good point. I'll try the PTFE. The problem is a relatively recent one. The windows used to close if pushed just past the click point. A good job really for a short armed person, hence having to lean half out of the window!

 { Is  that  a  young  James  Arness  of  Gunsmoke  ??  }

 You've a good memory. James Arness as Marshal Matt Dillon along with Chester Goode played by Dennis Weaver. I saw it as a kid in the 50's, I hadn't realised it didn't finish until 1975!!!!