If you remove dust container then switch on the upper connection to the cylinder provides the suction thro the the machine. Switch on and if you have plenty of suction replace cylinder and remove lower access port right hand side with the machine in font of you for normal use. Switch on if there is no suction or very little the problem lies with the yellow part which is attached to the handle of the cylinder.
This is held in by 2 tork15 screws found underneath the upper filter.
This part has an inner skin and the only way I have found to clean it once it is removed from the upper filter is by holding it in you hand and tapping either the vaned end on to a flat surface or by holding in hand and tapping the side with all the holes in int your other hand.
Hope this helps
Doug
December 2007