Well, I was just over 9 hours of a 10 hour print, and, after a few minutes, noticed that the filament had completely run dry... just a tad frustrating, as it was an absolutely perfect print up until it ran out, and started "air printing". However, my first concern when it happened wasn't the unfinished print, but what kind of mess might have been left in the extruder, as there was filament just barely sticking out from the "nubbin" (can't remember the technical word for the upside-down V protrusion just below the extruder motor. I was really concerned that it would be: a) extremely hard to pull back out, and b) potentially block if I try pushing filament in behind it. Bit of background: I've only ever changed filament before, and I did it by raising the temperature of the extruder to around 100 degrees, and carefully pulling it out. This seemed to work perfectly, and came out all in one part. I finally got it to work: I cut the filament at a right-angle (hoping that there was more chance of it pushing the old filament through), setting the extruder to 210 degrees, and manually feeding (using the front-panel) the filament through. I put a small mark on the new filament to ensure that it was feeding through evenly. I have a few questions, if that's okay: 1) Is my approach to filament changing, and what I did in this case okay? 2) Is there a (better) way of telling if filament is about to run out, other than watching it? 3) Has anyone encountered a blockage when changing / running out of filament? Is it as problematic as I imagine? I have another question about the extrusion calibration (going through half a dozen iterations, changing esteps, I still can't get exactly 20mm)... I seem to end up increasing the e-steps by 10 each time, and still ending up with 24mm left after the extrusion 0 test print. Touch wood, it seems to work fine anyway... Many thanks in advance.