Report "I have an Airco rotary tool and bought a flex shaft, not a Dremel flex shaft, don't know what kind, but it seems I need a square nut to attach the shaft to the Rotary tool, cause the ends don't work when it's attached. Does that sound right? Can I buy a separate square nut? I see the Dremel Flex shaft comes with it, is attached to the back of the packaging, mine didn't unless I accidentally discarded it, though I don't think I did"