A.O. Smith motors are labeled as being counterclockwise rotation and are shipped that way. Apparently, the quality control has slipped and quite a few motors are in the marketplace and on your efm stokers that may be turning in the wrong direction.
Looking into the fan housing from the outside at the shaft end of the motor, the fan should be turning in a counterclockwise direction. If it is not, there is a reversing switch located on the back of the motor under a black plastic plug. Move the switch to the correct position.
In a typical home, where 4 teeth of feed is used, and the motor rotation is clockwise, you might have had to add more air than the recommended setting to burn the coal properly. In larger applications, when 6 or 7 teeth of feed is used, an air setting of 10 will not be enough air. If you have red hot coals falling off the edge of the burner pot and adding air doesn't correct the problem, check the motor rotation first.
If you have changed the motor rotation, you must readjust the air setting. Start with the recommended 4 feed/4 air setting to obtain the 2 inch wide ash ring.