phild 2018-1-18 10:39 edit
I think I have a problem with extruder/calibration.
My first couple of prints were excellent, I then unsuccessfuly attempted to print using some conductive black which resulted in the extruder hitting the build platform and a blocked extruder. I managed to change the extruder with some difficulty as it was very tight, I noticed that when the replacement extruder was in place that there was some vertical play and on further inspection I noticed that there are just 2 screws holding the heater/extruder instead of the 3 shown in the site images.
The result of the vertical play is that the calibration varies depending on whether there is filament loaded (i.e. some pressure on the extruder from the feed motor). I suspect that the play resulted in the extruder moving slightly downward due to pressure from the conductive black PLA.
My questions are.
Should there be vertical play in the extruder once fitted.
Should there be 2 or 3 screws holding the extruder/heater to the extruder assembly.
Other than that the printer is fantastic, so easy to assemble and use.