Hello, I recently purchased a 1948 john deere b. Charging system not converted. Still has the 6 volt positive ground. Noticed the Amp Gauge barely moves toward charge if at all. Tractor has been cranking progressively slower. Obviously not or only barely charging. I grounded the field terminal and nothing changed. I got the model number off the generator, and bought a rebuild kit and matching regulator (based on the model number). Rebuilt the generator and installed new regulator. Polarized it. Charging system seemed to slowly work up to around 6.9 volts, but then after about 10 minutes running it dropped back to 6.3 volts and stayed there. If I turned the lights on it dropped way down. I grounded the field terminal again and it went full charge. So it appears to be a regulator problem. After doing a little research it seems as if the three brush generators are supposed to have a "cut off" not a regulator. What I got was a two coil regulator. The one I took off was also a two coil regulator. Any ideas would be appreciated. Thanks.