goo AKA heatsink compound is not optional. Try a fresh dab of it from CPU to the heatsink.
I have an ancient (like cavemen used, lol) HP ze1000 laptop. I am a fairly competent diy'er; I just removed MOBO and soldered on a new power jack. Reassembled with only 1 screw leftover :-). Anyhow, now the laptop works (and charges) flawlessly. But it will suddenly just.turn.off. I think the problem is overheating of the cpu. I cleaned up the fan, heatsink, etc while it was apart. When I removed the heatsink I set it on a glass surface. I didn't realize there was goo on the pad that would come off. As I said, I got the whole thing back together and have this new problem of shut down after 10-15 minutes or so. I intend to install some sort of free or shareware for temperature monitoring. But I will not power it up again until the heat issue is resolved.
OK - for my question: How do you know if the fan is shot? The fan & HS are separate. Does a HS go bad? I can find a "used" fan pretty cheap, (but I already have "used" one, right?). Can I just apply a dab of new "goo" (arctic silver, etc) and pray? I don't want to go the professional route; this is a recreational laptop that I play simple games and browse on - it is not worth professional repair. I have fun opening things up and am not afraid to do so. I always do thorough research - I don't just crack it open and prod around with a stick. Any advice, links, etc are very welcome.