For sensor, just try to use those ball ball "BLOWER" first, ( make sure it is clean, sometimes dust INSIDE ).
You can actually SEE if there is any dust/etc on your sensor....
Sensor swap will be the last thing you want to use.
You can use sensor brush as well, but they are pricey, I just use sensor swap myself.
Even most camera come with self cleaning system now, I still do my own clean up. ^_^ |