Is there something wrong with the Fan? Any 120mm fan will pretty much work
Stock Fan spec as follows (120mm):
• 600 - 2000 RPM
• 21.2 - 76.8 CFM
Just stick with the same brand and you'll get the same performance - http://www.coolermaster.com/cooling/case-fan/blue-led-silent-fan-120mm/ - if you want to improve the 212 performance, add a second 120mm fan.
or this one http://www.coolermaster.com/cooling/case-fan/sickleflow-120-2000rpm-blue-led/
Corsair AF or SP 120mm fans (AF will give better cooling performance, SP will be quieter)
http://www.corsair.com/en/air-series-af120-led-blue-quiet-edition-high-airflow-120mm-fan-twin-pack http://www.corsair.com/en/air-series-sp120-led-blue-high-static-pressure-120mm-fan-twin-pack
Just Google "Blue LED 120mm PWM Fan"