Need better pens! The first time I used it was on a 580c body stabilizer bar cylinder. Iron stuck, bad! But my first try with a new wrench just broke both large diameter pins! I didn't even put much pressure on her. I switched to smaller diameter pins, tried it on a smaller cylinder and it worked fine. So I went back to a larger cylinder with smaller pins. So far I haven't managed to unscrew the screw, but the small pins haven't broken off (with great effort), neither have the big ones.