Today I am driving to the Apple store to have them look at my iMac. This will be the 2nd time that I had Apple look at my iMac for what looks like dirt under my glass. Back on February 8th, Apple replace the LCD along with the back light due to what looked like dirt under the glass in the upper right corner. Two days ago, I noticed this vertical black bar of dirt on the left side of my screen. The question I am asking is, how many times should I just keep getting it fixed? Or should I just ask Apple to give me a newer 2012 iMac?