It looks like a fairly new (2000 model) unit. That grinding noise
sounds like the gears in the small motor that turns the table. It's
not too difficult to change after removing the whole unit and taking
the cover off. The motor is probably $30-40, but that is just a guess.
If you have the oven built in and need exactly that sizing then it
certainly pays to have it fixed in this case. If you are not fixing it
your best bet would be to remove the unit yourself and take it
somewhere, which would save a service call. You can call GE and get a
price on the part for starters. They also offer service help for a
price.
If your model is not designed for use without the turn table then do
not try to use it that way as there will be hot spots in the oven.
Food will cood unevenly and burn.
In my opinion, the turntable is a failed invention to make people feel
better about the even cooking of their oven, when in fact, a hidden
stirer does a better job and is the more trouble free, life of product,
system