automatic vent problem

[sweetcorn]

I went down to the green house yesterday for first time in about a week (work gets in the way of gardening, doesn't it?) and the pane of glass had slid out of my automatic vent. I retreived it and slid it back into the frame. But now it appears that it isn't opening automatically - it got quite warm yesterday and there's no sign of it moving.

Anyone know how can I fix it???

[Capsid]

I'd remove the piston from the frame and inspect it functions properly. Do this by warming it up and cooling it down to see if the piston is moving freely.

[meggalley]

I would take it out and follow the intallation instructions as if you were starting from scratch. There isn't a lot to go wrong with them so it's probably just got stuck.

Meg