My post May 2010 iMac 27" quad core started to grow brown blotches on the LCD monitor. 
As I live close to the Core repair center in Jet Park so I took it in on Tuesday.
They phoned yesterday(Wednesday) and said the LCD panel needs to be replaced, and that they had spare panels in stock.
Today, Thursday I was phoned and was told that my Mac was ready for collection.
I think a repair within 48 hours is fantastic for us in SA.
Thanks to Antonio and his team.
Well done Core Technical, Jet Park.


PS. This is a reported problem on Google.
As I live close to the Core repair center in Jet Park so I took it in on Tuesday.
They phoned yesterday(Wednesday) and said the LCD panel needs to be replaced, and that they had spare panels in stock.
Today, Thursday I was phoned and was told that my Mac was ready for collection.
I think a repair within 48 hours is fantastic for us in SA.
Thanks to Antonio and his team.
Well done Core Technical, Jet Park.
PS. This is a reported problem on Google.