Dirt Devil DD9001 Manuel D'instructions page 10

5. Put the filter cotton into the filter cover as shown in figure 1 and 2,
then align the "unlock" symbol of filter cover with triangle positioning
rib on the main body. Finally, rotate the filter cover to the "lock" in
sequence according to figure 3, 4 and 5, as shown below.
(Pay attention to the slot position)
6. Align the symbol on the dust cup with the "unlock" on the filter,
assemble the dust cup onto the main body, as shown on figure 1.
Rotate the dust cup in the direction of figure 2 after it is installed in
place. After installing in place, the symbol of the dust cup faces the
"lock" of the filter, as shown on figure 3. Then push the dust cup
switch upward to the "lock" position, as shown on figure 4. (Note that
the dust cup switch is unlocked before the dust cup is installed.)