They blog a lot about their repairs process in general. It's primarily mechanical damage to lenses they appear to normally deal in - the focusing rings, apertur

They blog a lot about their repairs process in general. It's primarily mechanical damage to lenses they appear to normally deal in - the focusing rings, aperture mechanisms or realigning optical elements dislodged by drops and so on. An embedded CCD/CMOS sensor is probably a full logic board replacement I'd assume, as opposed to some kind of sensor only replacement, given it's almost always soldered on.