Extruder Jitter while extruding

Hey, new to 3dp, so forgive me if I say something stupid- but I've got a very strange issue going on with my extruder. . .

On pronterface during calibration everything seems to work great. But, when I start a print with the test cube the extruder motor simply rocks back and forth- jitters. [www.dropbox.com] You can see (and hear) what I mean at 00:18.

I'm using a Prusa Mendel with Makerbot J-Head, 3mm fillament. If you need more info let me know!

Do you have retraction on? If so, then it's normal for the extruder to move back and forth. Is filament being deposited?

I'll have to double check that tommorrow but yes it is extruding, im concerned that it's not the correct amount. Also concerned about the noise that it is making when extruding.

Your extruder is missing steps - check the current on the driver.

Fist of all check the alignment and mesh of the extruder gears. The herringbone gears give a really solid drive system but alignment is critical. BY their very design they are intolerant of misalignment.
By simply increasing the driver current you may be just masking the issue

Good luck