I had a major issue with a print overnight and came back to find our Ultimaker 2+ a little worse for wear with various pieces bent out of shape and melted PLA attached to multiple components.
After resetting/recalibrating everything, it is mostly behaving however the material (still PLA) is not feeding properly - it keeps concertina-ing inside the print head (see attached picture).
I've tried all the usual things with the feeder, cleaning the printer head, re-threading the PLA etc but the same thing happens again as soon as it starts to print (but seems OK when using 'Move Material'). I don't know if its related, but there is a whole load of melted PLA stuck in the printer head which I cannot get out (see other attached picture).
Does anyone have any ideas?