I have dust just behind the glass on my rear screen, and just inside the view finder. I have had some success removing a small hair from the sensor, dust on the mirror and on the bottom of the prism, but I'm afraid to take anything else apart. Recently I used a lens cleaner inside the body and it left fiber lint on the black felt like material. It is rough to be non reflective. I was able to brush it out with a lens brush but i had a few loose bristles fall out. I was able to get these and then put the lens back on. Some good instructions and the correct tools would help. The camera is at least 2 yrs old and has never been serviced but used a lot.