I have a '51 AD 3/4 ton with a new generator, new voltage regulator and a new battery (all 6 volt).

The problem is that the ammeter showed a good charge (about half way between 0 and full charge) up until a few days ago. For a while the ammeter showed that the system was discharging, but now the needle sits almost exactly at 0, showing a little bit of charging at higher RPMs and a little bit of discharging at idle. Turning on the headlights moves the needle to the discharge side.

What should the readings be? What might have happened? What can I do to get the system functioning properly?

Thanks in advance.

Rob