Hopefully im not too late posting this but i only just stumbled across this site trying to fix my laptop lol,
you can safely take out the heatsink if you unscrew the 4 black ones and the 3 silver ones holding the whole heatsink down, this gives you easy access to clean any lint or crap out of the fan. I did this yesterday and found a block of fluff that was making my fan work overtime and overheat LOADS. try and have some heatsink compound aswell to replace the stuff thats on there originally as when i took mine off it was like bluetack.
hope thats your problem solved now im off to post mine lol.