My left headlight is not working. The only bulb that works at all time is the signal/marker bulb. I have the two bulb headlight and none of the white lights turn on, I'm also not neglecting the fact you need it all the way to right not centre. I could hit it and it can come on or off, then it stopped turning on completely. Is there a common problem associated with this? Certain know wire issues. New bulbs installed and di electric grease on connections.

 

Had an issue once. Try bending the connector that the bulb plugs into so that it pushes on the bulb a little more. Mine got a little weak and had to pry the connector out just a little so that it made a good connection.