2003 C230 Kompressor Coupe Manual Light adjustment

Hi All, As I am new to this car I am looking for some guidance. When I bought the car 3wk ago I noticed the manual headlight adjustment turn wheel (inside car on right of driver side) was on the lowest setting, hence headlight lighting road only 5ft infront of me. So, I turn it all the way up - after doing this I can hear a light "hissing" noise from this switch/turn wheel. The lights however have moved up thus suggesting the motor is working. Any setting other than the lowest setting you get this light "hissing" noise???

Any ideas what it could be?
Is it a normal C class thing?
Should I just ignore?

Cheers Guys.