New TAZ4 printer weird extrusion noise when printing slowly

Another issue I have I am a bit worried about is noise I am getting sometimes when extrusion happens slowly. You can hear it this video:

Also extrusion gears have some amount of plastic dust on them - I wonder if this is normal or something missaligned or misstighted somewhere.

Sounds like you are getting a bit of filament grinding. I’d try tightening the extruder latch springs a bit. If the extruder tries to push more plastic than the model has space for, it can gouge the filliament and cause some dust like that.

thanks, i will try to experiment with tightening screws differently.