iPod nano, iPod touch, and iPhone screens: repair or replace after 1 or more dead pixels iPad: repair or replace after 3 or more dead pixels
MacBook, MacBook Air, MacBook Pro 13″ and 15″ models: replace after 4 or more bright pixels, 6 or more dark pixels
MacBook Pro 17″, displays up to 20″: replace after 5 or more bright pixels, 7 or more dark pixels iMac 24″ and iMac 27″,
Apple Cinema Displays from 22″ to 30″: replace after 9 or more bright pixels, 11 or more dark pixels
If the number of pixel anomalies is within specifications, explain that to the customer. Further explain that you can replace the product, but the replacement product may have even more anomalies yet still be within specifications, and that Apple will not replace the product again if the number of anomalies in the replacement product is within specifications.