So I get my new E3D and am happy. I spend most of the evening installing this thing because the grub bolt fell off never to be seen again, so I had to replace that with an M3. . Finally, it's all wired up. The thermsistor is appropriately placed, is hooked up, and is not shorted. The fan is installed. Filament feeds down into the head (measuring it) while cold, so I know it's unobstructed. The fan is functioning properly (I wired it into AUX1). I modify the software for a maxtemp of 300C and a temperature sensor type 5 as the documentation instructs. It compiled. I upload it to the printer. Looking at version messages, I verify that the new version is running. Oh, I'm supposed to set it to 290C to start. That's what the assembly instructions say. It seems to heat up slower than I would expect, but I attribute this to the fan. I do verify twice that the fan is running. I wait. I fuddle with the filament screws (seriously, who came up with that design?) and chase the things as they fly off into the wall a couple of times. All of a sudden, the bottom falls out. What this thing has done is melt itself and melt part of the X-carriage. So clearly, a few things happened here. The thermsistor didn't work, because it read 280C (!) when all this happened, and it's physically on the heat block. Their heat dissipation system obviously didn't work, and their own part melted. 2: 3: Any bright ideas? And I should have printed a spare X-carriage before doing this, but obviously I didn't foresee this happening. It was going to (ironically) be one of the first prints I did with the new head.