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Why do big box stores don't carry good quailty electric chain saws? All I
could find are so-so electric chain saws, many with non metal gears that
will be stripped in time.

Because thats what the average DIYer wants. If you want a decent chain saw
go to a farm store or good hardware store and pick up a sthil or even a
upper end polun(sp) etc. Expect to pay a couple of hundred bucks+ but you
will get a good saw.