Interestingly enough the 3DS uses just standard small screws. I was able to buy a jeweler's kit from Wal*Mart to open mine. If your's happens to have a tri-wing screw, those screw drivers run for like 1$ on ebay.similar however i dont have the tools or professionalism to soldier / desoldier so i dont mess around with chip on a board parts
The best way to determine if this is the same as mine, is to just list the system near your ear and gently shake it. If you hear something bouncing around or loose, you may have something hardware wrong with your system.
Normal wear and tear. Most of the parts aren't actually soldered down, they are held in either from friction or clips.So what do you think could have cause the problem in the first place? If you didn't abuse the system or anything like drop it, why would it just suddenly move itself around without enough effort?