For consistent filament extrusion with a LulzBot 3D printer, be sure to check that the idler springs have proper tension. Lulzbot TAZ, Mini, and any other printers that use a Wade’s extruder require an 8mm (or slightly less) spacing between the outer faces of the washers that contain the idler tension springs.
You can 3D print your own handy tool to quickly set the correct tension on the extruder filament idler springs!  Download it for free here: Lulzbot idler tension jig