I may have spoken too soon on my previous excitement about this printer. I've cross-posted this to Google Groups, but thought maybe someone here may have a repair solution, in case Wanhao doesn't come through.

My unit printed fantastically for a couple days, but now it doesn't seem to be able to heat up the extruder reliably. When I tell the machine to heat to PLA temperature, or load a GCode file, the temperature does nothing. It just sits at room temperature, and heats up a few degrees (to maybe 30 or so) from the radiated heat it absorbs from the hotbed. Then, if I play around with the cables, it will randomly start heating up. Sometimes (as in the attached video), it will heat ALL the way up to extrusion temperature. However, if I start actually printing something, it will immediately fall back down again, eventually back to room temperature.

https://www.youtube.com/watch?v=Nv4X3aZnNdw

I've contacted Wanhao, and they were initially fairly responsive, asking for more photographs. I provided more photos, but haven't heard back from them yet.

As a side note, I've also noticed that my unit is missing the vertical "CNC drag chain", and instead they've just wrapped the wires in something less protective. I'm wondering if that indicates that they had a problem with the wiring on my unit, played around with it, thought it was fixed, and then shipped (without replacing the drag chain).