I got a piece of gunk on my sensor somehow, so I brought it in for a cleaning (I'm a bit too nervous to do more than blow on it gently with my Giotto bulb and that didn't get rid of it). The service tech got the big stuff off, but tells me that there is a fair amount of dust between the filter and the sensor that he wouldn't even try to get to -- he said the only way to get at it is to send it back to Canon and he's not sure what they'd charge ( or if they would even get it all). I'm not sure it's worth the expense, they're barely noticeable and I can clone them out. Has anyone had this problem? What did you do?