Anthony, you are correct about the fan. The fan is used to cool the magnetron during cooking, and because this fan is not working the mag is overheating and the thermal protector is opening, killing power to the unit, until it cools back down. All you need to fix this is a new fan blade. The fan blade is slipping on the motor shaft ( the noise you are hearing). The new fan blade fits tighter to the shaft to prevent this from happening again.