my power supply fan is crapping out. i opened it up and cleaned up the fan but its still not working very well... it starts spinning, but after it speeds up it wobbles and loses speed and does this over and over again. should i try to find a replacement fan or just get a new psu?
Firstly, it sounds like the OP's psu fan overheated, evaporated the oil from the oil-impregnated bearing, and then ground or abraded the shaft at that point. When it speeds up, the shaft starts wobbling therefore. Simply put, the fan is bad and must be replaced.
Secondly, the psu is no more dangerous to the careful person than the rest of the computer. The sharp metal edges inside it are arguably more of a hazard. To make your psu as safe as possible, turn off the system and leave it off for about 15 minutes. Then unplug the psu from everything, take it out, and plug the wall cord back into it. After another 15 minutes, there's no significant chance that some component has enough charge left to injure you, much less kill you.
However, replacing just the psu fan is fairly tricky. As other posters noted, the fan may be soldered into place, or it may have just a plug ... but that plug may not be standard enough to find a replacement without resorting to some soldering on your own. After those concerns, it's relatively hard to find those fans. They're called "muffin fans", since they're sort-of muffin shaped. Finding one that fits your exact size and voltage is going to be tough.
If you're just not any good with handling such components directly, it's probably best to toss the psu aside and get a new one. If you've an electronics-handy friend, maybe he'll put a new fan in for you, in the first place. If he won't do that, he might appreciate having the psu anyway since he can always do something with it.
There's a possibility that the fan is OK and the periodic slowing down is due to a faulty power delivery from the psu itself. The fan is likely to be 5 or 12 volts DC, which must be fed after the psu's rectifier circuit. If the rectifier is pulsing like that, then you're obviously going to need to replace the psu anyway.