Go back to step 8, where it says to pull the cord out and wedge a screwdriver in the spool to hold it under tension. If you have no cord on the spool, you'll have to rotate it to put the spool under tension, then wedge a screwdriver in to hold it, insert the new cord, tie the knot, then remove the screwdriver to release the tension, so the spool will wind the cord up.
