Could there be mice eating wires in there?

It is entirely possible. They've been stealing the bait out of the traps in the basement. Are you saying the wires could be compromised and therefore creating these strange sounds? They are consistent--not animal sounds. And then who do I call--the oven serviceman or an electrician?

What do The sounds sound like?

Wish I could upload audio--wavering in modulation, kind of a grinding, scraping, moaning, going up and down in pitch.

That sound was the 80s calling you to turn the oven breakers off, although 220v will cook a mouse pretty fast.

:-D

I can't find parts diagrams for the stated model (are you sure that's the full and correct model number?). Does it perhaps have a mechanical clock/timer? If so, that mechanism may be worn and making odd noises.

Yes that's it, so it must be really old. I can't find it on line either. I'm suspecting 1999-that's around the time some of the other appliances in the house were manufactured. There is a timer/clock, and that's where the noise is coming from--that area. I turned off the circuit breakers and it's night and dark down in the basement--will turn them back on in the morning and see what happens---that and call the electrician.

1999 is not too old for parts diagrams at the two site I specifically referenced. 1987 may be depending on when GE purged older models from their database. 1975 would be for sure if it's that old.

It's entirely possible that it's from 1987.

Upload a video to YouTube and post it here.

I wouldn’t open the oven if I were you. Call an exorcist.

It's probably the clock/timer motor. When they loose lubrication, they can make a weird grinding, moaning noise.