My 1984 boat has a backstay adjuster made by Barbarossa. It has two handles that fold down after being used to turn the threaded mechanism. Harken acquired Barbarossa, but they seem unable to find anyone with a knowledge of the thing. It looks like this link except it's got black anodized aluminum arms.
http://www.harken.com/productdetail.aspx?sku=B1722
When you loosen mine, the upper tube and its cap stay fixed to the upper stay, and the actual threads appear above the handles. I think the tube and cap are supposed to keep the threads covered as the stay slides up. Before I test my theory that the cap is just seized to the stay and that giving it a good whack along with some lubricant might fix it,I thought I'd try to confirm that I'm not about to destroy my adjuster
