If it doesn't work after adjusting the turnbuckle, either it's toast, or was adjusted improperly by previous owner. To adjust them, you have to remove them from the crankshaft, disassemble, reassemble using an adjustment gauge, and reinstall.
Pretty straightforward, but there are some difficulties that can arise in the process, the most major of them being the set-screws that hold it onto the bearing/crank. They can be a real pain. Get out the PBlaster now!