if its appear clean...than its due to a weak wiring... as with time... now it needs an addition of relay to the headlights and add a xenon head lamp instead of normal halagen... or if u don't wish to change to white lights than use the halogens of philips or osram. no china...
chek the bulb first make sure its not chinese.... before goin for polish or changing the bulb.... moreover halogens' are normally 60/50 watts whr as xenon comes in 100/110 and 200/230 watts... so choice is urs .... xenon's are good quality of korea