I was given a little GN 125, I suggested to my friend who was given it, that it was too cute to be left sitting outside rusting away. Next thing I knew he'd dropped it round to my house. Anyway the headlight bulb was working but black so I bought another one, it has an American pre-focus bulb. I went out after dark and it was dipping to the right, changed back to the original bulb and it dipped to the left. I bought and tried another APF bulb and that too dipped to the right.
The original bulb has one filament horizontally across the bulb and the second one V'd over the horizontal one but in a vertical position. Both the new ones I bought have the two filaments horizontal one above the other. I phoned every stockist I could find of APF bulbs but they all had the two horizontal filaments.
Neither of the bulbs have a deflector inside the bulb just the filaments, I ended up taking the cheapest option and changed the headlight. I did try changing the orientation of the lens and the bulb itself but only ended up with a tall narrow beam which never really pointed where it should have.
Colin