Loosening the screw is the last thing you could do before the arm needs replacement. It doesn't solve the problem correctly, it just fixes it for that moment. There is another bearing under the arm inside your SL-1210. That top screw is just tightening the arm to the holder from the top. If the bearing at the bottom is broken there is no chance to fix it without replacing the whole arm. If the top screw on the arm is too loose the arm will be vibrating a lot and you will hear it on loud sound systems. It helps sometimes hoovering out the dust from the center of arm. It helped me for now with the problem I have in my gramophone but anti-skating is not working properly yet. I will try to open it one day and clean the bearing inside. Unless the bearing balls are worn out, otherwise it would help.