Auto vent problem

Ive got a solar window opener on my greenhouse window, sometimes it sticks open, but at least its open and not closed……i need to add weight to it, to try and help it close better at night.

 

The pre-install proceedure involves chilling the device in your fridge, if I remember correctly......

 

Mine were jammed this year and have been jammed in the past, so I added some lithium grease to all the moveable bits and the piston, that has done the trick. They are about 10 years old now