I think I have more dust (and/or cat hair) in my machine, affecting hard drive or fan, which is now making noise. ~2 years ago it was dust, Apple cleaned for me. It's hard for me to make it back to Apple now (2 little kids at home, can't be without machine for days). I've never opened my current machine - would people advise against trying to vacuum dust myself? Any obvious or not-so-obvious pointers if I decide to open up?