Been there..Retreiver. I've had an Ultra Foodsaver for over seven years which worked great until after I had packed 100lbs Albacore and then more salmon a little later. I thought it was the pump clogged and called Tillia. They sent me new black gaskets free of charge. As I have since learned... when it doesn't draw a vacuum it is best to check the renticular gasket for particles and if it is seated ok. The time it has not drawn a vacuum...I simply pull up on the gasket and set it so it is level. I think sometimes it gets pushed down so much that it doesn't provide a tight vacuum chamber. You can also pull out this black gasket, clean it and flip it upside down and reseat it into the groove but not pushed down all the way. Just some tips I have learned after I have BEEN THERE! I have corrected no vacuum problems about five times this way.
Hope this helps. I still love my Foodsaver.