I bought an artists brush and cleaned it according to the instructions here:
http://www.prime-junta.net/pont/How_...ur_Sensor.html
A rocket blower charges it with static and I then gently sweep the sensor clean. Easy. The only problem is that artists brushes have something called fining on them which needs cleaning off. That took several cleans. Fining free artists brushes are sold on ebay.
Needless to say, a certain degree of care is needed. It is fairly easy if you have a modicum of dexterity.
Leif