Hold time was only about 15 minutes before I got a tech. I explained the situation, he asked me some questions and I performed a few diagnostics and things for him. He somehow concluded that the smart extruder was faulty and got my shipping info for a new extruder (I have one customer who's on his 3rd extruder on his 5th gen, and I have another 3D buddy who returned his entire machine after the 2nd extruder quit working). I figure that the drones in tech support are just programmed to send out a new extruder instead of using real logic to troubleshoot stuff, but that's probably what they're taught. I know the company has been growing like crazy and they're probably having trouble finding good help. I get that. But i don't see how a new extruder is going to fix a bed that won't mechanically level. Who knows, maybe it will?

But, while on the phone I did learn a few useful tidbits.

The business part of the extruder moves up and down on the Z axis, about a mm or so. It can sense when it touches the bed, and it can also go up and down. That's pretty cool. Teaser - when you build, when most printers raise the extruder or lower the bed to do a Z-lift, the 5th gen raises the extruder - it's cool to watch.

I asked him how the machine senses Z limit, as I didn't see any limit switches like all our other printer, including the Rep 2. He said that it was a laser. Later in the conversation he said it was a hall effect sensor. I don't know exactly what it is, but there certainly aren't any mechanical switches visible anywhere on the machine, not just for the Z axis, but for the X and the Y as well.

As for how it is actuated to move up and down, I'm not sure. I know that on the high speed pens plotters I used to design, we used a voice coil driven by a linear amplifier to moved the pen up and down.