Why is suction power of a vacuum cleaner weak?

Why is suction power of a vacuum cleaner weak? 

Symptom

          Suction power is low

cause

          Suction power can be reduced when a dust bin is full.

How to fix

           1. Press Push to open a lid on the dust bin.

           2. Grab a handle on a dust bin and gently take it out by pulling upward.

           3. Unfasten a hook at the back of the dust bin to separate a filter and sponge.

           4. Vacuum and brush well enough to completely remove fine dust from the sponge and the filter.

           ※Washing the filter with water can decrease the suction power. Clean the filter on a weekly basis to maintain cleaning performance.

           5. Open up a cover while holding Open button.

           6. Empty the dust bin with a cleaning brush or wash it under running water.

           7. Dry the washed product in a shade.

           8. Put the sponge and the filter back to their original positions after cleaning the dust bin.

           9. Assemble the filter and the sponge together.

           10. When assembling, click in the rectangle-shaped part to the cover.

           11. Check if the filter and the sponge are firmly assembled with the dust bin.

           ※If the bin is assembled without a filter or filter cover, dust can go inside the product causing malfunction.

           12. Put the dust bin back in the Roboking and close the lid.