text / images burnt onto imac screen

I have a late 2011 imac 21 inch and after a year faint blurry fine llines apeared on the left hand side of the screen from top to bottom, very faint but visible under the right conditions. Now if I open my calander for 3 min there are fine lines across the screen with very visible text burnt into the screen. The longer the computer runs the worse it gets.

Takes about 20 min in the morning to start showing the fine lines again. I can still see December on my screen after half an hour as I type this.

What is at fault? the lcd panel? the logic boards? What?

Is it worth repairing myself?

Love apple hate this one machine.

Thanks

Philip Muir