Many times the cause of this is a dirty filter screen. This screen is usually located in the water tank. Try cleaning it to see if you get your suction back. If this doesn't work, next I would tighten all of the screws that you can find on the bottom portion. There are six on the top and two inside near the roller brush. Do not overtighten them though. Outside of that, call Bissell. They have a wonderful technical support department. Their phone number is on the bottom of the machine on the label that contains the model number.
www.bobsroswellvacuum.com
September 2008