I have two boards in one of our Elementary Schools that have dark spots showing up. They are only visible when the projector is turned on. One of the projectors (WPRM-45A) is a week old! The other is a WPRM-32. I have tried wiping it off with a soft cloth and water and it still is there. We also tried wiping off the outer lens and it still made no difference. Is there anything else I can try?