Cable busted.....so I need to replace complete support which includes cable. Support is held up by five screws. The three screws on one side came off easily because they were threaded into frame...but the two the other side don't seem to be threaded into frame like the other...they turn but don't come out....I can hear a click each time I turn-sounds like a clip maybe but there is no access to remove. Nothing in manual on this either. Hope someone can help. Thanks in advance, K