Hi
i have a up mini printer. the printer prints all fine but then it
- starts printing in the air
 - or sometime stops generating the filament.
 
And additional question,
- 
can i shutdown my computer when the printing codes have been sent to the printer and its start printing?
 - 
do i need to clean the head of the printer? and how to clean ? thank you
 
thank you. am newbie to 3d printer.