What does Best Buy replace in refurbished PS3's?

-so my 40 gb PS3 finally went down a couple weeks ago, and i'm looking to get another. The reason it went down is cuz the bluray laser diode that reads the disc burnt out, and it's like $150 to replace it, so i figured why not get a better slim? At best buy they have 'em refurbished for about $240. What i want to know is if the disc reader gets replaced, cuz i don't want to buy it and have it break in a year or so...slim disk readers dont break