If under warranty we can get this replaced. You can fill out a parts request by following the instructions below.
Please fill out the parts request form found below and we can send you the part you need. http://coolermaster-usa.com/partrequest.php
Use the model number of the cooler(RR-212E-20PK-R2) and in the description box state you need the fan replaced or accessories kit.
The serial can be found on the cooler’s fan connector on a white sticker. If you cannot find the serial number, then a copy of the invoice must be uploaded.
when done with request please provide me the parts request number so i can approve the request.
Thanks, but I've managed to resolve this for now. I took the fan off and used isopropyl alcohol spray on the cooler/fan and it seems to have gone away. It's about 2 years old so I guess there was some dust build up.