This is continuation of the review by edreview. GE after replacing the transformer again, spark module did not fix the hum. Then they tried placing some isolation tape under the transformer, did not work. Started isolating each electrical component one at a time by unhooking each item and plugging in the power. We able to find a second transformer for the LED lights. Place some isolation tape on the transformer and it worked. The transformer is located on the underside of the unit behind an access cover. To check you just have to remove the access cover and the hum went away. The access panel was touching the transformer. A simple fix with out GE would be to buy two rubber washers and place between the access cover and the base so the transformer so it does not hit the access cover. The technicians could not find this transformer because GE does not indicate that it exist in any of there diagrams.