You can replace the fan if it comes down to it and you're willing to take the risk of opening up a PSU..I have done it a handful of times, no real biggie..You need to cut the connectors off of the ends (because they're different) and wire the positive to positive and negative to negative.
But as stated above, the PSU has residual voltage that can kill or injure.
What's in it now is a Globe Fan RL4Z T1352512HH, 140mm, 12V, 0.45A, 1200rpm, 129.76 CFM, 38.8 dB, Teflon Nano Bearing fan..You can just use an equivalent/approximate 140mm case fan.
That PSU should have a 5 year warranty, so you can RMA it if it's still covered.