From your original post, first time the regulator was changed it helped for a while. Maybe it is just a bad regulator. It would be worth trying another.

Also grounding of the regulator case can be a problem. If it is not well grounded, no charge. It grounds where it mounts to the firewall. Paint or rust can prevent good ground. I would clean the firewall around the mounting screws and scrape some paint off the back of the regulator around the screw holes to make sure there is good ground. To be really sure, you can add a ground wire to a clean engine ground.