Noise was probably from High Voltage section of microwave, not an area for amateurs (no offense), and, Parts are Generally Expensive (GE).
The microwave oven is one of the most dangerous appliances to repair.
The high-voltage potential combined with the high-current capability of an operating microwave oven pose a deadly threat to the reckless worker. In addition, microwave ovens are radiation-emitting devices. Normally this does not present a problem. However, improper replacement methods or tampering with safety systems could expose the unwary troubleshooter to dangerous levels of microwave leakage. Therefore, extreme caution and proper procedures MUST be used at all times.
If you are uneasy or unsure about any of these safety procedures or warnings; or if you feel uncertain as to their importance or your ability to manage them, it would be in your best interest to leave the repair to a qualified professional.
We, the unwilling, led by the unknowing, are doing the impossible for the ungrateful. We have done so much, for so long, with so little, we are now qualified to do anything with nothing.