[MikeK]

If you disassemble the ammeter you can bend the needle that much. The needle is rather thin aluminum, much like a throw away pie tin. It takes two pair of tweezers and a very light touch. You also need to watch how close it is to the face when you put it back together.

Not being a D'Arsonval meter movement, it is influenced by surrounding magnetic fields and the magnetic permeability of the car/panel/gas tank itself. The earth's magnetic field will also cause it to read slightly differently if the car is facing N-S vs. E-W. That said, you need to correct the needle the amount shown as 'off' before removal from the dash. If you set it to zero on the bench it may not show that when back in place!