Check the integrity of the foam gasket that seals the port to the bins. Mine got pushed out of position. If that seal isn't tight then you won't get suction below the bags. Also, I have to be careful when lifting the bins. There's enough slop in the mechanism that it's easy to be off-center and again break that seal.?
The dial you refer to isn't a pressure/suction adjustment for the bins, it's the differential pressure trip circuit that shuts down the machine if the filters get too clogged. The adjustment is for varying levels of differential pressure.
