Furling refers to stowing or dousing a sail by flaking (folding), packing (like stuffing a spinnaker into a turtle), roller furling or just lowering it onto the deck. Nowadays, it is becoming more common to use the term "furling" to refer to reefing a sail that is part of a roller furling system. To reef the main sail means to reduce its sail area. ...
It takes more than you might think, and you want a few full wraps around the drum when the sail is all the way out so that when you reef, the load is distributed around the drum.) Pull on the furling line to furl the sail.
If the sailfurls, but will not furl once the sail is attached to the drum at the tack, the halyard is wrapping around the top of the furler.
You will need to add a wire pennant to the top of the sail so as to allow the head swivel to be 2"-3" down from the top of the furler.