When pushing the surface vent fan button on the keyboard the fan makes a squealing noise. Microwave fan works noise free.
I'd say the bearings are getting dry. I'd hit it with a a drop of 3-in-1 oil or sewing machine oil. If you don't have the owner's manual, you can download one here: http://www.geappliances.com/service_and_support/literature/ It's also possible that the keeper which holds the fan blade assembly may be broken or loose. That could cause the fan to slip and rub. Either way it will have to be disassembled to a degree, probably starting with removal of the grille. Exploded views of this model may be helpful. They can be found at this site: http://www.geappliances.com/shop/prts/ Under 1 select "Repair Part", under 2 select "Microwave" and click "Go". A window will pop up and you'll enter your (complete) model number. Good luck.
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