[butch]

How old is the power supply. If you just got a noise and then it ran my guess is its got some crap built up in it. id clean and lube it and see if that fixes the problem. Fans get very dirty by nature. I use one of those little bottles of oil that comes with a fishing reel. Its got the needle to get the oil into the inner part of the fan without getting it all over the place. Clean it and put a drop or two on the spline that goes into the motor.

I suspect that will fix your problem without have to spend any money.