Buzzing front lights?

[Stilo J]

I've just joined the Fiat Stilo family with a car in need a little TLC. One fault is that the right front main beam buzzes when switched on. The sound is like a motor that is sticking. The light still works but when I take the bulb out, the buzzing continues. It doesn't buzz with the side lights on. The front left doesn't buzz but doesn't work currently anyway. Any advice gratefully received - I've no idea what is causing this and it sounds terrible.

 

[Stu DemonD]

Stuck light leveller, common problem!