Diagnosis
Dust accumulation on the external lens surface is projecting shadows onto your screen. The lens has a multi-layer anti-reflective coating that is easily damaged.
How to Fix It
Use a two-step process. First, use a rocket blower (like those for camera lenses) to dislodge loose dust. Never blow with your mouth. Second, for remaining smudges, use a microfiber cloth designed for glasses or optics. Gently wipe in a circular motion from the center outward. Apply minimal pressure.
If That Didn't Work
If the specks remain in the exact same screen location after cleaning the external lens, the dust is inside the sealed optical engine, on the DLP chip or an internal lens. This requires professional disassembly. Contact support.
Heads Up
Never use liquid cleaners, window cleaner, tissue paper, or shirt fabric. The coating is delicate. Always replace the magnetic lens cover when the projector is not in use to prevent dust accumulation.