As pointed out in another thread, my sensor in my Canon 7D is filthy. I've spent the better part of an hour trying to clean it, with no luck. It appears to me like some kind of oil spots? I use a rocket hand blower first to remove any dirt and debris. Then I run a soft brush from a cleaning kit over it a few times. This did nothing for the original splotches on the sensor. So I got a drop of isopropyl alcohol on a spot of a microfiber cleaning cloth and rubbed it out....... even this didn't work! Back to a clean cloth over a Q-tip and buffed over it a few times. Nothing. Two shots of the offense below. Any suggestions?