Not sure why it felt heavier after you got it back...I just took mine in to get the top case replaced. Its an 06, 1.83 core duo. Never had applecare, warranty expired years ago, the genius said they will replace all defective top-cases once, even if you're out of warranty. Just FYI, they WILL fix it for free if you've never had them replace it before.
how about the palm rest crack will they fix that too?
07 macbook 2.16GHZ
yeah thats the top case, Thing is my whole case was replaced in October - under warranty, well everything except the bezel that goes round the screen, And thats the bit thats now coming apart. Also the bottom enclosure is also cracking again, near the fan vents and at the front near the ridge to open it.