I bought this machine a couple months ago and have only sealed 10 bags with it. I got it out today to seal some hamburger. I made 12 bags and when I went to seal my 1st bag it started to vacuum and 4 seconds later the vacuum shut off and it started to seal. It had not taken any air out of it before it started to seal. i tried all the solutions you gave and still nothing works. This is the 2nd unit that I have had. and the 1st one did the same thing. I just thought the first 1 had been overly used but this one has only sealed 10 bags.