DIAGNOSIS This is almost always a loading or alignment issue. The rotisserie motor isn't very powerful, so if the weight isn't balanced or the spit forks aren't locked in, it will struggle or stall.
FIX 1) Make sure the spit is fully inserted into the motor socket on the right side. You should see the square end of the spit engage deeply. 2) Check the two spit forks. They must be pushed firmly into the meat/chicken and then the thumb screws tightened securely. The food needs to be centered and balanced on the spit. 3) Before closing the door, manually give the spit a spin. It should rotate freely without the left tip dragging on its support. Adjust the food if it's lopsided.
IF THAT DIDN'T WORK If the spit moves freely when you spin it by hand but the motor still won't turn it, the drive mechanism inside the right wall might be jammed with grease or debris. Unplug the unit, let it cool, and use a pipe cleaner or small brush to clean the square socket where the spit inserts.
HEADS UP Trussing your chicken or tying a roast with kitchen twine is not optional—it's critical. Loose wings or legs flopping around will throw off the balance and can jam against the heating element, causing the motor to stop.