I would also like you to check the filter wheel and motor control board. Make sure that there are filters at positions 1 and 3 and blanks at positions 2 and 4. Also, make sure that the wheel is securely fastened to the lid (and is not “wobbly”) and that the metal interrupter strip is not bent. Pictures of this would also be helpful. Also, make sure that the chopper motor is phased correctly and spinning in the correct direction