For mine it was in the dead center of the screen. At first, yeah Im fine with it, but after a while and seeing a pixel that stays lime green the entire time your playing becomes a hassle. If I bought a 72 inch flat panel tv and had a dead pixel in it, would I keep it with that malfucntion, no I wouldnt it, I spent good money for a product that I want to be good. If you bought a computer and it had some glaring issue (such as a missing P key on the keyboard) would you keep it, most likely not. Likewise, if I bought a DS that had a dead pixel dead center, would I keep it, no I wouldnt. I paid, I value the worth of the product and I want a nice product, thus I use the warranty to get one.
I wouldnt do it after the third try cause after that point and still receiving a faulty equipment, I would just buy a new DS lite and hope that works, as I did and it has. Saved me time, phone call/internet time, and I got an even more better beautiful looking colored DS Lite.