Oh yeah, Husse, any time anyone opens a case and starts pulling things out, there is a large chance of breakage (as well as smoke and fire). As for the thermal compound, one trick I have used is waxed dental floss. It is just right for getting between the heat sink and CPU without causing any damage as it releases the bond. Of course, if the compound is holding on tightly, chances are that it is good. If it is flaky/crumbly/dusty, then replacement could be considered.
Now, that being said, kilometerage may certainly vary from person to person. I have used the dental floss method on Socket 5, Socket 7, and AM2 only, and I have always been extremely careful. As Husse says, do not break it if you cannot fix it. I would start with compressed air and blowing out the dust bunnies first of all. Have fun!