Some times its because the bag isn't flat across the sealing area. Other times I find it works better to flip it over. Some times I grab hold of the bag near the edge of the machine to pull it flat and let the wife close the cover. I usually put something like a thick phone book or stack of other magazines in front of the machine. This allow the bag to be more in line with the sealing area and helps to keep it flat. The longer the bag the easier it usually is, allow yourself some slack. I hope this helps.
"gene"
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