Vic Baron wrote:

Should I try to clean the upper bag and how? Doesn't seem like there's
anything to 'empty' but appears that there's a fine coating of dust
along the walls. Would this result in reduced suction? I guess I could
try a shop vac.

The upper bag will get a fair bit of fine dust, which will clog the
pores and reduce airflow. DON'T use a shopvac right up against the
fabric, as the airspeed is too high and could damage the fabric.

Try just holding onto the fabric at different spots and shaking it. You
should see a fair bit of the dust cake just fall off and into the lower bag.

Chris