I would like to direct your attention to the picture of the dryer drum. We know that the air stream exits the drum through a filter in the door. Now consider how the air enters the drum, through the center of the back of the drum. There is a stream of air through the center of the drum, from front to back and, granted, a large load tumbling through it will diffuse it somewhat, but why not have an area around the center of the drum back solid and have the air enter more toward the periphery, through part of the areas that are solid in the picture, and be pulled through the drum toward the center to exit through the door mounted lint screen? Norge did something like this with the air coming in through those 3 ducts at the rear of the drum and exiting around the door (and other places via air leaks). It seems more efficient than having so much of the drum blocked from the air flow. It would also be far better for drying small loads which often follow the periphery of the drum instead of dropping through the center where this dryer's air flow is.