The most common and probable problem you're having is due to a failed magnetron. GE spacemakers are famous for failing magnetrons.
Is this something that i can replace myself?
You're capable, yes. It's not typically something I'd recommend a customer do themselves though. It requires pulling the microwave down and removing a lot of screws. I would like you to check your manual though because, depending on the age, the magnetron may be covered. It's an expensive part.
Ours is about 6 years old. How expensive?
I'll need your model number. It's probably on a tag inside the cavity on the left side.
I need to go downstairs to get it. Be right back.
Ok, give me a minute or so.
WB27X10017 is the part number. It lists for 130 bucks. The manual states your magnetron is covered 5 years. With the loud humming sound and the fact it won't heat, there is a 99% chance it's bad. A bad magnetron can cause the high voltage diode to go bad too, but not usually.
You can buy a new microwave for twice the price of that magnetron. It's usually not worth it unless the mag is covered.
That just answered what I was typing!!!!
I have ESP apparently lol
Thank you and we will look into the price of a new microwave. You have been very helpful!
You're welcome. Have a nice holiday.