Not defective or out of spec, but they purchase in such large quantities that they can have the item made to match their price point. I related an old story last time this came up about a friend of mine, also an EC, who bought a Milwaukee Hole Hog from HD. First time using it on the job he was boring some 2" diameter holes through studs. He didn't even get the first one done when the chuck stopped turning and the motor kept going. Felt like a gear stripped. So he brought it back to HD for a replacement. Now with the replacement drill he goes back and tries to finish where he left off. No sooner does he start another hole then he same thing happens again. So this time he gets a refund and gets another drill from an on-line tool supplier. It cost a little more but Interestingly enough, no more problems. So it's clear that Milwaukee likely skimped on heat treating the gears in order to sell cheaper to HD.
However, I don't know how much of that goes on anymore with nearly everything made in China. The manufacturer is paying bottom dollar to the Chinese manufacturer so they can afford to cut a deal with major purchasers without sacrificing quality.
-Hal