The M9 I recently purchased needs sensor cleaning. Many little occlusions, which sure looked like dried moisture spots on the sensor. I've tried the blower-brush, and tried lens cleaning solution on the single-use lens cleaning wipes. Hope that's safe, so far no scratching from my efforts that I can tell. The problem is getting the moisture residue off. It's just tough to get the entire sensor free of that. I've tried the lens cleaning cloth that came with a kit to try gently rubbing those out with little circular motions. Breath on the cloth a bit for a small amount of moisture or try the lens cleaning solution on the cloth, or just dry. Any tips or suggestions toward a thorough cleaning? Perhaps use a Q-tip behind the cleaning cloth to get a small, controlled rubbing surface?