Stop Extruder Jams!

Do you ever have random extruder jams, where it will skip a layer or air-print? You have a nice spring-tensioned, ball bearing extruder, yet it still has occasional jams? This finally fixed it for me.

The filament guide is not the key; there are plenty of those here already. The key is wrapping it with felt soaked in oil. This is the product of a brainstorm with people on the Makerbot google group and some folks at Makerfaire.