Just walking stepwise through the assembly mentally - the graphical instructions for the extruder assembly don't mention any bearing - isn't there one visible as part of item #11 (single extruder idler)? It carries no part number, though, and is also not mentioned in the parts list. But there should be something to push the filament to the hob. The dual extruder graphics also does not mention it. Just curious... Cheers, U.