CA light switch problem

I have restored a 55' CA.  I am having a problem with the light/charging switch.  I recently replaced it because the lights were on when in the 3rd position.  It is the same with the new switch.  As i understand it from the service manual, 1st position it is suppose to be low charge, 2nd position, slow charge and lights on and 3rd position fast charge and lights off.  The needle moves with full range a magnet moved over it.  When the battery is not even hooked up the ammeter reads 4 on the charge side.

It's working like it should. All the way in low charge lights off. Out one notch high charge lights off. All the way out lights on high charge.

I always tell my customers to run an aux. ground circuit off the mounting screw that holds the switch in the instrument panel to the steering post where the Pos. ground cable is normally connected. This is an added insurance which helps to make sure the switch is grounded. When folks restore these Tractors, they may paint or get some overspray into the inside of the instrument box. Paint is a great insulator of electrical grounds, so make sure the area where the switch is mounted is free of paint or rust. (make sure that the Battery ground cable has the same cleanliness) A Rolox pad on a drill works great for cleaning up the area before installing the switch. This helps eliminate non charging issues, blown fuse at the switch, & burnt resistors. The 6V system relies on its proper grounding in order to work correctly!    HTH.