I've cleaned so many of these that I've lost count. They are easy to clean and all you need to do without removing them from the bike is: Get a 1 inch paint brush (or smaller) Spray the brush lightly with sone window cleaner Remove the bulbs Put the brush into the headlight and brush the headlight glass until all the bulb dust has gone Leave the bulbs out for a while so that the inside of the glass can dry Put the bulbs back in!
I use white vinegar window cleaner on mine as it dries totally without residue. This not the cheapest place to go to but it will give an idea of what the product does. Household White Vinegar Cleaning Spray - 500ml - Natural Collection Select
I used windolene on my 996 and worked a treat. Didn't have the brain power to use a brush as Tonka suggested and instead used a pencil with cotton wool wrapped around the tip with an elastic band.
My version consisted of a small rectangular washing up sponge, with half a lint free duster wrapped around it, secured to the end of a drum stick (musical, not food) with a cable tie, squirt a dollop of Windowlene (OMAA) on it and insert through the bulb holder hole. Wiggle, wiggle, sparkle. Quick, easy, repeatable. Also, and if your feeling like a bit more sprucing to the H/L unit - if the black paint edging around the edge of the clear glass has gone ragged and tatty, you can mildly warm (eg.on a radiator) some bog standard electrical insulating tape and stretch all the way around the edge of the light lens. Gives a nice crisp edge that is more durable than the original.
