The fan located in the freezer has been making excessive noise. After removing the cover and exposing the fan, I can silence the noise by placing my finger on top of the shaft that comes out of the white plastic fan. I am guessing the bearing has gone bad in the motor but have no real idea and do not want to spend 70 dollars on the motor unless I absolutely have to. Please help with any suggestions as to what must be done to solve this noisy problem. Thank you.