I have the Foodsaver too, not the gamesaver. Once in a great while it won't pull a good vacum but that is rare. Only suggestion would be not to store it with the lid "locked" down...it collapses the foam-rubber seal too much and leads to the above mentioned problem. Other than that I really like it!
Been using a FoodSaver Pro II for all kinds of grocery items all year, lots of fish in the summer/fall and tons of duck, goose, & deer from fall / winter. It's only needed a new bag cutting blade chingas that wore out. I've had major long term sessions when bagging my Tuna as well as my neighbors and never have had a heat issue but this was the best unit they made at the time.
I understand the top of the line Gamesaver now has 2 motors to increase the power and reduce the machines work load.
Aaaand Costco has a $30 coupon off the foodsaver package right now...which I might add I just bought a couple months ago and it performed flawlessly for an entire freezerfull of fish. Just a thought for you...also, why not go with what has been tested and proven for years? Rhetorical question of couse.
A suggestion I have for you is something I do myself when vacuuming fish.
Dry the fish off throughly before putting into a bag. Seems to vacuum better, but the big plus is that it eliminates smelly fish water getting into your vacuum machine. Before doing this I had to wash my machine out every time or face the wrath from my wife. In her defense it does get a little, ah, rank after a couple of days.
Since starting the toweling thing I seldom have to wash out the vacuum.
A friend of mine goes further. He wraps his fish in seran wrap before vacuuming. He claims it gets an absolute vacuum that way.
My method works for me.
Aslso before I forget. Buy a set of replacement rubber seals for whatever unit you have.
I bought mine at the Fred Hall show so now and then I pickup a set or two, changing the seals every couple of years.