The electric systems always have corrosion around the ground connections on the frame;check the ground connection(bare metal to bare metal) around where the coils mount to the frame & make sure the metal is shiny & around where the battery box mounts to the frame & where the rectifier mounts to the battery box,etc.
The electrics are the weakest system so they need the most maintenance; I think if you took a bit of time to clean ALL the connections & coat them w/ dielectric grease, you will have a solid system that you can build from.