And I use a very long bag when I empty the bin.That way you don't get so much dust blowing back up the tube I also hold the bag tightly around the bin to seal as much as possible then I don't come into contact with a dust cloud.
Okay, the entire cyclone assembly is clean and dust free and the filters were washed. Starting from tommorrow I am going to use the Dyson until the dirt gets to the max line which may take a day or two, this is without emtying of course. When the bin is full, I will take out the pre filter and look in the filter compartment, if there is no dust inside the housing of where the filter sits then I will be convinced that, the culprit is emptying the bin and dust statically raised up the tube.
I find that to be a problem when emptying that the dust goes up the tube, but only like an inch. I clean it out before installing, but the average user definetly will not which causes fine dust to go through the motor.
My Dyson DC40 has done the same as yours since day one, I will have had it one year this April. The cyclones have always had a layer of fine dust inside as well as the suction inlet for the motor. At first I was concerned about this, but being its been almost a year and no problems have come of it I've kind of let it go. "Let it go" "let it go" OK I'll quit singing.....Also I've only washed the filters twice since I bought it cause they never get dirty! I find this kind of weird, but in a good way. Only thing I have noticed is that the post motor filter is turning black...Even after its been washed, probably carbon deposits from the motor or fine dust that's been getting through over time. Here are some pictures below.
To be honest Alex i think the dust you see at the bottom of the cyclone is dust blowing back but the dust at the top inside the filter housing looks like dust escaping. I can honestly say that has not happened with my machine i would say if it had i've no reason not to i'm not being paid by Dyson. I always give my honest opinion of all the cleaners i use.
I will try to take a clear photo later to show you.
Anyway why not call out a Dyson engineer and ask him to tell you why this is happening and to put it right or you want your money back.
Haha it is. A little dust in the filter tube is not going to do any harm but it should not be caked in dust. Those cyclones should be throwing the vast majority of dust out of the airflow. According to Dyson down to 0.5 microns so I hope it works for you.