Doesn't seem to suck the bags down all the way, or doesn't suck them down all the way to where it will automatically go to Seal?
One thing you might try before throwing that thing away and buying a new one is to treat those spongy little strips that help it seal. Those can dry out and it won't be able to seal any more. Get a bottle of Mineral Oil from your local pharmacy. Just costs a couple bucks. The smaller the bottle the better. It's odorless and tasteless. Pull those spongy strips out and wipe them down good with the Mineral Oil, and wipe off the excess. Put them back in after treating, and you may be pleasantly surprised.
If that doesn't work and you still have to throw your vacuum sealer away, the remaining Mineral Oil can be used as a laxative. LOL