Possibly the angel of the mirror is out of focus. If I'm right you could loosen the arm of the mirror with a screwdriver placed in the holder, turn it a bit in, fix it and make use of the new "angel window" of the mirror itself. Or is this method only possible with round mirrors anyway...
Tried that with the factory fitted round mirror but the only way the passenger side mirror could be used was if the arm was in the most upright position. Not only does this look strange but it gives a poor view for parking or reversing into the garage etc.