I also bought the arm and am actually very satisfied. However, I have one problem: to adjust the screen tilt, it has 3 hexagonal screws that fix the "ball joint". I must have loosened and retightened the screws a little too often and by now there is not much left of the six edges of the screws... meaning I can't tighten the screws enough to adjust the screen as I want. Can anyone tell me what replacement screws I need to buy? Unfortunately, I can't find any information on this in the operating instructions.