It sounds like the fan is out of balance and its by far the loudest fan in my computer. Not only that but I'm pretty sure its getting worse. Is there a way I can fix it myself (by replacing the fan or something)?
Problem is that I'm pretty sure I made it this loud because I forgot to turn the computer off when I was tilting it to get air out my loop, so I don't know if I can send it back under warranty or not. The other fans seem to be working fine and are pretty much silent.
Tilting the computer while it is running should not affect the PSU fan. More than likely, the fan is defective, and like you correctly diagnosed, it is probably out of balance or has a bad bearing, or both.
If you are handy with replacing parts, you will not have any problems replacing the fan. Just make sure you get a replacement with equal or better CFMs.