Trickle Vents

[LIZS]

Have only recently heard of these and think our wooden, thinly double glazed windows may have them. We do suffer with condensation about this time of year so thought opening them may help but am unsure how they work . Some seem looser than others, do they pull inwards, slide ? Looks like first image top left

They look like they slide.

If you can see a way to take then off (e.g. small screws) clean off dust and cobwebs with a small paintbrush, wash the plastic parts, lube with furniture polish. Start with a downstairs one in case the outside part falls off.

Thank you . There is a little screw. Some of them have slid a little to the left and inwards, does that sounds right ? How far should they open ?

Couple of inches, probably, or half their width.