I did use the Windex, and hopefully it took care of any dirt and dust that was there. I am having some one from Freedom Scientific call me back because the tech I talked to has no idea what may be wrong, he though it had lost focus and told me how to get it back, but it didn't help. Patti Me and my guide dog; He does a good job, He keeps me safe So life is just great For me and my guide dog.