Firstly check that piston rod is located in the hole in the top block. The rod is designed to disengage in windy conditions and may need to be reset manually. If the piston has stopped working you may be able the slide the piston assembly out from the bottom block following loosening of the m6 bolt in the block. Earlier models have a smaller diameter hole in the bottom block that will not allow the piston assembly to be withdrawn. In this case a new complete ridge autovent will need to be purchased.
Buy online today..
Gabriel Ash Reviews
The only timber greenhouse company endorsed by the Royal Horticultural Society