might be a sticky relay in the regulator, or a loose connection on/in the generator or regulator - did you polarize the gen when you re-installed it and regulator?
"When we tug a single thing in nature, we find it attached to the rest of the world" ~ John Muir "When we tug a single thing on an old truck, we find it falls off" ~ me Some TF series details & TF heater pics