When I ordered my cold frame a number of years ago, I also ordered an autovent cylinder replacement because they wear out after while and need to be replaced. Well I got the new one out and come to find it is far too long, I don't know if I ordered wrong or was sent the wrong part. Anyway, the place I bought the cold frame from doesn't seem to be in business anymore. After some internet searching, I found a limited number of places that sell them, many do not provide measurements of the parts. Does anyone have a reliable source for autovent cylinder replacement tubes?

Thanks!

In looking more at my replacement piece, it might be that it is the right size, but maybe it is broken.