A10 Extruder stutter

[Chaoswill]

Help.
I am quite new to the 3D printing thing and have recently purchased an A10 which is more that adewquate for my needs.
In the early days I have designed and printed a couple of basic items (Box and Lid, Mobile phone case etc) succesfully with the standard settings, but a couple of weeks ago the Extruder stepper motor started to stutter after about 2 minutes of printing. It will feed for that initial 2 minutes, then enter a mode whereby it quickly withdraws about 1-2mm of filament, then slowly re-feeds that 1-2mm, then withdraws it again, then repeat..repeat..repeat (like its cought in a loop) throughout the rest of the print resulting in no print at all.
Any suggestions??
Will