My turntable on my GE Spacesaver xl1800 isn't turning...there is a noise which happens when it tries to turn....is there something that I as a homeowner can do instead of calling a repair person?? thanks

The motor assembly is fixed to the base of the oven usually with two screws and access i obtained by removing the inspection plate directly beneath the motor. It is usally a plug in synchronus motor that revolves at a few revs per minute but the plastic cogs in the motors gear box fail and the motor assembly must be replaced. They are fairly inexpensive and obtainable usually from a domestic appliance repair shop.
If you feel confident, disconnect it from the mains power, remove anything in the cavity and turn it upside down if it is a tabletop model, a little more complicated if it is built in!
Remove the inspection plate and disconnect the motor. Remove the motor and go and get a new one. Re fit it and put the microwave back in its position. Plug it back in, with the turntable and plate. Put a cup of water on the plate inside of the oven and heat for 20 seconds to check the plate goes round.
Hope this helps.