I have glass headlamps and if all else fails I use the same trick the car trade uses to get overspray off the windows, very fine wire wool (the finest you can get), it doesn't scratch glass and leaves it spotless and if you doubt it then a little research will show you that 0000 grade is used to cut back between coats of Varnish, French Polishes, lacquer, varnish, oil finishes and paint in the furniture trade and also used to clean and polish metals such as bronze, copper, chrome, stainless steel and aluminium, it can also be used with soapy water to clean and polish porcelain, marble and glass without marking.