Temperature regulation

If you're dropping 20C, that tells me you fan is blowing directly on the nozzle, which is confirmed by you later on as well. Fix that by sliding the insulation forward so it sits even with the face of the nozzle, just like the instructions say.

If the pin is slipping, you'll hear it. It sounds like it's slipping, from the "struggle and lurch" comment.

Pictures would help, like insta said.

Just slide the insulation forward - I don't know what the problem there is?

It is definitely assembled incorrectly. The white spacers go between the flanges, not behind the back one. The lasercut spacers can go on the back of the back flange if needed.

The 1/4" sticking out refers to how much of the auger sticks out of the barrel (so the other end from where you measured).

I'm still 95% sure the hex socket is slipping based on the other things you described. Just because you can't get the hex socket off doesn't mean it isn't slipping. Leave the hopper mostly empty so you can watch the rotation of the auger. Mark it will a sharpie, you should see 3-4 RPM.

No, I mean sticking out of the barrel:

It should be sticking out 1/4" with the thrust bearing compressed.

Don't worry about the spacers on the picture, you have an older revision than pictured.

Finally back from holiday vacation and getting around to messing with this again...

I took the insulation off of the collar to reposition it properly. I'm guessing that the heating band is improperly installed, and should NOT be flush with the rear edge of the iron fitting like this? It should probably be towards the forward part of the iron fitting, perhaps flush with the front edge of it, yes?

Also, i rebuilt the flange assembly but this doesn't seem right. With ONLY the nylon spacers between the flanges, the compression bearing is extremely loose. You can see in these next two photos that there is probably a half centimeter of play. I'm not sure what's wrong here, but it definitely doesn't look right?

I see, thanks. Didn't want to try running it without asking about that first.

Its up to you, really. The mechanical fuse (washer) was a great idea in theory. It worked well on my workbench, but didn't work so well when the various washer thicknesses came into play.

If you contact me through the contact form on the Filastruder website, I can send you a square shaft/gear assembly. You pull the back off the gear motor and swap it out. The only other option is to try a thicker washer.

The new shaft (along with the other assembly corrections) is working great. I'm getting almost exactly 450 mm/minute extrusion and tolerances of +- 0.04 mm (not including where it kinks due to not falling towards the floor properly).

I'm running through a day of extrusion to clear out contaminants before I try making any filament for actual printer use, but so far so good!

It's pretty clear though that I need to use a winder. I can't let this sit for more than 10 minutes before the coil twists badly on the floor and causes either a kink, a thick/thin section, or an outright knot of filament at the nozzle exit.

Also, is it normal for the power supply to run very hot? Almost too hot to touch with bare hands - about like bare metal left out in the July sun.

I assume that if I mount the extruder vertically that the filament guide will be irrelevant then (the fan still would matter, of course)?

I'm planning to donate/loan the operational machine to my local makerspace, and would likely end up mounting it vertically on a wall or post.

For now, it's just been running horizontally on the edge of my workbench - only about 30" from the floor. Perhaps operating at the height you suggest (and vertically so the extrusion doesn't kink as much while soft) will be good enough that a winder won't be needed. Probably best to just try it and see.