Dear Sir,

sorry, lately answer your question, and every days was very busy, and i operate a trading company on construction materials, such as plywood, MDF, furniture, etc. so have much work to do, and just login fixya meet all warm heart friends by off hours.
meantime, i'm amateur of electronic products, and glad to answer some question what i know, kindly hope i can help someone.
under the support of many friends who comes from Fixya, i open a ebay store, specially supply projector, and DLP HD TV sapre parts, such as color wheel, DMD, lens, lamp, boast, mainboard, remote control, light tunnel, etc.
sorry, saying so much words, back to your question.
firstly, inspect the connect cable, then note some outside signal disturb, if you exclude these two reason. perhaps you should find a repairman help you to remove dusty. if all these action can't solve with your trouble, you have to think about the reason of DMD.

hope above words be useful for you,
for any further communication, please freely contact me,
best regards
Jack,
email: [email protected]
when you need projector color wheel, lamp, mainboard, DMD, lens, etc sapre parts, please don't hesitate to contact me,