I have a SilverStone 600W ST60F modular PSU that's only about 3 months old. For the past week, its fan has been making a loud rattling noise. (I'm 95% certain the PSU is the culprit. It's possible it's the CPU fan. I know it's not the case fan because I've already replaced that to try to fix this problem and the noise is as bad as ever). The blades appear to be striking the circular metal shield. Should I loosen the screws to attempt to lower the shield and separate it from the fan blades? Or is this a bad idea on the theory that One Should Not Mess With a PSU? It seems awfully early for the high-end PSU to be failing, and I'd hate to replace it if the problem is easily fixable.