Has anybody ever done one? How easy is it to do? My trusty 27inch iMac from 2009 is having its very first breakdown and the symptoms suggest a new graphics card is needed. Don’t fancy going via Apple due to the cost and age of the machine. Thinking if I try and fail I’ve lost nothing or anybody got any idea of what the trade in value would be via apples program? The sites down presently so I can’t check.