greysun

For us the majority of the problem worked out when we switched pla filament brands. The brand we got from ultimaker was broken on every spool in dozens of spots and was very brittle. Each time it would hit one of these breaks or one of these brittle spots it was unable to push filament forward so the filament would just sit in the nozzle and cook until somebody discovered it. Also if you're using ABS it's going to be tough without a climate-controlled system. I built an enclosure with temperature regulator for ours and that helped. we had to go through several different brands of filament before we found one that worked. We wasted over a year messing with this setting or that setting and whatever before we finally realized the filament was the problem.

We have been battling with issue like this for months. 15 hours into a 60 hour print the thing just stops extruding. We have been playing with all sorts of settings, retraction, fan speed, print temp. Even different brands of material. Nothing seems to help. I just fired off another 60hour print. I am trying to print at a little higher temp. If it works out I will let you know. If you hit on what works let me know. I am beginning to think the reported temp on the ultimaker is reporting higher than what it is. To answer your question about the tube above, it looks fine. The scratches look like the external ones cause by the clips.