I'm inclined to give it to a professional to do. Martin at Martin's Camera Shop has had professional photographers come in and says "this doesn't work" – the don’t RTFM. He sends it to these guys at fixation (http://tinyurl.com/23a3yw
) and one of the technicians has spent 30 years at Canon and now is employed by fixation. Martin said there is nothing he doesn’t know about Canon equipment. The guy at fixation will say there is nothing wrong with this camera; they need to check this setting and so forth.
The cleaning process is a delicate matter, so change your lenses in an area were dust etc is not whirling around. A good place is a car.
The first time you clean your sensor you are an amateur and you risk damaging the sensor and de-calibrating the mirror. These guys will clean the sensor until it is dust free and check the calibration of the mirror and anything else that may concern you.
You can go there, pay your £49.75 and it will be done in 25 to 35 mins.
If you clean the sensor yourself, you must use high-quality fluid; swabs and brushes so why not just pay the money and let a pro do it.
Look after your camera but let the pros mess around with the guts of it.
I’m an IT engineer and network engineer and I have had clients spend days trying to fix a problem because they thought they could do it. I get it and fix in with a couple of clicks. They are amazed and say how did you do that and how is it you know so much. Why because this is my job. It’s flattening being called a genius too.
I don’t fix cars because I don’t know anything about them so I would go to a reputable mechanic.
A little knowledge can be a dangerous and expensive thing. Be smart and seek out a pro.
They service Nikon too.