palo

Hi. Does any one have any idea how straightforward it would be to swap a cd mechanism from a working cd unit to a non working one? I have been quoted approx £140 to do this but I have a basic knowledge of electrics and have removed my old audio system. The replacement unit I have is not the premium model as it is from an is200 S rather than the SE. Also what are anyone thoughts on replacing the OEM with an aftermarket unit. Thanks P