i had exactly the same problem, the main thing is that the lights are on canstantly which is draining the bettery. It sounds like there is nothing wrong with the regulator if there is 14+ volts getting back to the bettery, try looking at the connector block to the regulator it might be curroded if so clean it off with some connection cleaner and either cover it in silicone or in grease and try running it without the fuse for the headlight in for a day or 2 and thats should sort it. chin_dragon