There are no sensors - it's all really simple. The motor has a sharp-toothed gear on its shaft. The filament is pinched between that gear and a small ball bearing just to the right of the gear when looking from the front.
About 10mm below the gear and bearing is a small hole that the filament has to enter - this is the passage through the block containing the linear bearings. If the filament misses this hole, the stepper will click. At the end of the passage through the bearing block is the feed tube which is part of the hot end, and at the end of the feed tube is the nozzle.
Did a little bit more fault finding, and it turns out that the main ribbon cable is faulty.
When it is sitting normally, all the way home and latched, the extruder motor does strange things (oscillates, goes backward, etc).But when I flexed it a certain way, the motor came to life.
I have sent a mail to Zortrax to see if I can get a replacement.
it might simply be that they changed to a black ribbon cable...but then you could still do my repair. the color of the cable does not matter...assuming it is still the same connector style.
I am guessing you have figured this out as this is an old post. But heres this anyway. lol
Cheers
Did you take the feeder motor out to see if there is filament blocked in the top hole? I had to drill out Zglass there before a few times because it broke off when changing the filament.
