Printer stopped 2 hours into a 13 hour print...
Had no power outage, nor are there any faults showing. Manual says it may be that the extruder fan stopped working, so my question is, does the extruder fan run constantly while printing or does it cycle on and off in response to a sensor. I started the print again and it seems to be running fine. Also, this is the second print of the item and the first printed perfectly so it isn't an issue with the design or the slicing. Thanks for taking the time to educate a newbie!
Clean the fans with a paintbrush or a blast of compressed air. If they are clogged with filament whiskers or hair a pair of tweezers might help.
If the fans fail or go intermittent then check the connectors are seated properly in their sockets. If the problem persists you might have a damaged cable; there are a couple of pinch points where damage can occur if they are overtightened. Replacing the fans can be avoided if you are confident enough with a soldering iron to splice in a patch.