Turn table turns some of the time
Check the turntable guide to make sure it is lined up properly and that there is no debris caught in it. You may need to re-align or clean your turntable guide.
Cleaning and realigning a turntable guide;
Remove your glass turntable cooking tray from your microwave. Gently wash with warm soapy water to remove any debris. Next remove the turntable guide and clean it in the same manner, with warm soapy water. Pay particular attention to the turntable rollers. There could be spilled food particles caught in the rollers, hindering the rollers' movement. Also, gently cleanse the internal cavity of your microwave, paying special attention to the area below the turntable.
With the internal cavity, turntable, and turntable guide completely clean and dry, return the parts to your microwave. First place the turntable guide on the bottom of the microwave. There should be a circular groove in the bottom of the microwave cavity keeping the turntable guide in place. Follow the guide with the turntable cooking tray. Carefully place the glass tray over the turntable guide and onto the drive bushing. The drive bushing should fit neatly into the grooves on the bottom of your glass cooking tray. It may take some adjusting before the tray will sit properly onto the drive bushing.
Test your microwave after this thorough cleaning and realigning in order to determine whether this has solved your problem. DO NOT run your microwave with nothing in it.
CAUTION: Your microwave oven is capable of giving you a serious electrical shock, even when it is unplugged. We strongly suggest you seek the assistance of an appliance repair technician when conducting any microwave oven repair.
Also, Examine the plastic drive bushing the turntable tray sits on. It may have become worn, or even may have split in two;
Drive bushing replacement
Inspect the plastic drive bushing located below your microwave oven's turntable tray. There may be some debris blocking the tray's range of motion. Clean away any blockage you find, and then test your microwave to see if this has cleared up the problem. DO NOT run your microwave with nothing in it.
However, if upon your inspection, you notice that the plastic drive bushing below the turntable tray is worn and/or broken, you will need to have the bushing replaced. Consult with a certified and experienced appliance repair technician. Replacing a drive bushing is a lengthy and involved process that the average layman should not perform.