To correct common problems with a FoodSaver vacuum sealer, check the roll or bags, leveling the device and ensuring that the area between the device and lid is clean. Also, make sure to not overfill the bags.
Suction problems are common with vacuum sealers, and if there is too much bagging material in the sealing chamber, the suction may not work properly. Use the line on the interior of the sealing chamber to know where to place the bag, and ensure that the bag does not go over the line. If this does not fix the issue, clean the area between the device and the lid. If suction issues are not present, it may be that the bags have holes in them.
Another issue with a vacuum sealer is that the bag gets a partial seal. This often occurs when attempting to seal items with oil, water or juice in them. The liquid may coat one side of the package, which means the bag cannot seal. To fix this, carefully place the bag into the sealer so that a spill cannot occur, and blot the moisture off of the food before beginning to seal. If this does not work, make sure the device is level, and then check that all of the plugs are in place.