This is just to get something up on the forums should someone else have this problem:
There is a little yellow plastic bit which transfers rotation of the distribution drum stepper motor to the shaft which turns the distribution drum. Should you find yourself having to replace this and discover that the drum shaft has simply vanished somewhere into the depths of the heater box, I can provide you with an elegant Jack-leg fix employing a 3/8" drive drill adapter. PM me for details.
There is a little yellow plastic bit which transfers rotation of the distribution drum stepper motor to the shaft which turns the distribution drum. Should you find yourself having to replace this and discover that the drum shaft has simply vanished somewhere into the depths of the heater box, I can provide you with an elegant Jack-leg fix employing a 3/8" drive drill adapter. PM me for details.