hi all been an avid reader and follower of the forums. lots of stuff here has helped me solve issues with my macbook pro retina 15. now i have two specs of dust embedded in my screen which can only be seen when you dim down the screen and view it up close. i am contemplating taking into an Authorized Service Provider but i'm just curious about their replacement parts. are they new or used? the reason why i ask is because i find it hard to swallow if it is indeed the latter as i would essentially be swapping out a new screen for an old one which could have a shorter lifespan than the screen i currently have. would appreciate any comments/feedback/suggestions thanks!