I opened up the Petite press iron curious as I am. on the left with red wires attached is the heating element bar, on the right with black wires is the temperature sensor. the temperature sensor is the feedback element that shuts the heating element off based upon which of the 4 temp settings its set to. the screw on the left of the iron is the set screw that holds the heating element on the floor of the iron; while the screw on the right of the iron holds the temp sensor to the iron via a small bracket thing. My guess is that variation between units may come from how tight these screws are; my theory is that if one tightened the heating element set screw perfect (not to crush the heating element) to maximize heat transfer, and to loosen the temp sensor screw a bit to minimize heat transfer such that it won’t tell the controller to shut off so soon. Obviously one wouldn’t want to completely disengage the temp sensor as it serves a purpose and likely prevents melting the plastic housing of the iron. I have performed this procedure on my unit and will test it on both the 210D and 40D fabrics once my boat supplies come in. also note that the heating element starts at about half way from the front of the iron to almost to the rear