I had to learn this. I first heard this from my boat manager but confirmed it in my Hood Stoway manual.
1. Head into the wind and ease the mainsheet. (Improves angle of sail to luff slot for furling)
2. Ease outhaul keeping light tension. (Ensures smooth sail furling)
3. Rotate the luff rod with the toggle switch, deflecting the switch in whichever way permits the sail to furl without bearing on the leeward edge of the luff slot (i.e. On the starboard tack furl in the counterclockwise direction and on a port tack furl in the clockwise direction.) If you are headed directly into the wind it doesn't matter which direction you furl.
It goes on to describe the function of the alarm buzzer. My boat is a 1983 Hinckley SW 59 masthead sloop. My boat manager has worked for Hinckley, was Henry Hinckley's personal captain at one time, and has known the boat since new. I do not know why I check him on this stuff, just curious I guess. I hope that helps.
We had a LH52 with hood furl and agree completely with the above advice. I would keep a wrap around a winch to create a little friction on the outhaul while pressing the furling button, playing one against the other. The issues occur if you don't furl it tight, it gets too big for the space in the mast and gets stuck. Then you've got trouble, especially if the wind is up.
Also agree winding into the wind so the sail is not rubbing against the aperture of the opening in the mast helps. In light wind, you can have a little load on the sail, that helps. In heavy wind, you need to point more directly into the wind. In all cases, watch it wrap, if it's not wrapping tight, stop, reverse, try again.
Deploying, same thing. Keep coordinated with the outhaul. Don't let the furler get ahead, it will bunch up.
At least on ours, the manual backup system was this little pulley that you attached to a pin on the mast. It drove the gear box that drove the furler with a lot of mechanical advantage (the gear box must of been 10:1 or something, you pulled on a line on the pulley a lot before you got a turn of the furler).
In 10 years of ownership, I never jammed it, but came close. It sure is convenient...no sail packing, and infinite reefing range. As long as you don't get it jammed.